vm: add VM_FAULT_SIGSEGV handling support

commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream.

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Jan Engelhardt <jengelh@inai.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[shengyong: Backport to 3.10
 - adjust context
 - ignore modification for arch nios2, because 3.10 does not support it
 - ignore modification for driver lustre, because 3.10 does not support it
 - ignore VM_FAULT_FALLBACK in VM_FAULT_ERROR, becase 3.10 does not support
   this flag
 - add SIGSEGV handling to powerpc/cell spu_fault.c, because 3.10 does not
   separate it to copro_fault.c
 - add SIGSEGV handling in mm/memory.c, because 3.10 does not separate it
   to gup.c
]
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[sw0312.kim: cherry-pick from linux-3.10.y to apply CVE patch]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I6f418ae2623b821f3949aa47e588497caff65226

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 98838a0..9d0ac09 100644 (file)
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -156,6 +156,8 @@ retry:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 50533b7..4b70fc3 100644 (file)
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -160,6 +160,8 @@ good_area:
        /* TBD: switch to pagefault_out_of_memory() */
        if (fault & VM_FAULT_OOM)
                goto out_of_memory;
+       else if (fault & VM_FAULT_SIGSEV)
+               goto bad_area;
        else if (fault & VM_FAULT_SIGBUS)
                goto do_sigbus;
 

diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 0eca933..d223a8b 100644 (file)
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -142,6 +142,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 1790f22..2686a7a 100644 (file)
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -176,6 +176,8 @@ retry:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 9a66372..ec4917d 100644 (file)
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -168,6 +168,8 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 7225dad..ba5ba7a 100644 (file)
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -172,6 +172,8 @@ retry:
                 */
                if (fault & VM_FAULT_OOM) {
                        goto out_of_memory;
+               } else if (fault & VM_FAULT_SIGSEGV) {
+                       goto bad_area;
                } else if (fault & VM_FAULT_SIGBUS) {
                        signal = SIGBUS;
                        goto bad_area;

diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index e9c6a80..e3d4d48 100644 (file)
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -200,6 +200,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index eb1d61f..f0eef04 100644 (file)
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -153,6 +153,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto map_err;
                else if (fault & VM_FAULT_SIGBUS)
                        goto bus_err;
                BUG();

diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c
index 332680e..2de5dc6 100644 (file)
--- a/arch/metag/mm/fault.c
+++ b/arch/metag/mm/fault.c
@@ -141,6 +141,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index fa4cf52..d46a5eb 100644 (file)
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -224,6 +224,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 0214a43..c40a8d1 100644 (file)
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -157,6 +157,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 3516cbd..0c2cc5d 100644 (file)
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -262,6 +262,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 0703acf..230ac20 100644 (file)
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -171,6 +171,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index d10d27a..c45130f 100644 (file)
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -220,6 +220,8 @@ good_area:
                 */
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto bad_area;
                BUG();

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index d9196c9..d51a0c1 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -425,6 +425,8 @@ good_area:
         */
        fault = handle_mm_fault(mm, vma, address, flags);
        if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
+               if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                rc = mm_fault_error(regs, address, fault);
                if (rc >= MM_FAULT_RETURN)
                        goto bail;

diff --git a/arch/powerpc/platforms/cell/spu_fault.c b/arch/powerpc/platforms/cell/spu_fault.c
index 641e727..62f3e4e 100644 (file)
--- a/arch/powerpc/platforms/cell/spu_fault.c
+++ b/arch/powerpc/platforms/cell/spu_fault.c
@@ -75,7 +75,7 @@ int spu_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
                if (*flt & VM_FAULT_OOM) {
                        ret = -ENOMEM;
                        goto out_unlock;
-               } else if (*flt & VM_FAULT_SIGBUS) {
+               } else if (*flt & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) {
                        ret = -EFAULT;
                        goto out_unlock;
                }

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 416face..d214321 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -244,6 +244,12 @@ static noinline void do_fault_error(struct pt_regs *regs, int fault)
                                do_no_context(regs);
                        else
                                pagefault_out_of_memory();
+               } else if (fault & VM_FAULT_SIGSEGV) {
+                       /* Kernel mode? Handle exceptions or die */
+                       if (!user_mode(regs))
+                               do_no_context(regs);
+                       else
+                               do_sigsegv(regs, SEGV_MAPERR);
                } else if (fault & VM_FAULT_SIGBUS) {
                        /* Kernel mode? Handle exceptions or die */
                        if (!user_mode(regs))

diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 5223898..6860beb 100644 (file)
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -114,6 +114,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 541dc61..a58fec9 100644 (file)
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -353,6 +353,8 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
        } else {
                if (fault & VM_FAULT_SIGBUS)
                        do_sigbus(regs, error_code, address);
+               else if (fault & VM_FAULT_SIGSEGV)
+                       bad_area(regs, error_code, address);
                else
                        BUG();
        }

diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index 59dbd46..163c787 100644 (file)
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -252,6 +252,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 3841a08..ac2db92 100644 (file)
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -443,6 +443,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 3ff289f..12b732f 100644 (file)
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -446,6 +446,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 5c3aef7..06ab0eb 100644 (file)
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -80,6 +80,8 @@ good_area:
                if (unlikely(fault & VM_FAULT_ERROR)) {
                        if (fault & VM_FAULT_OOM) {
                                goto out_of_memory;
+                       } else if (fault & VM_FAULT_SIGSEGV) {
+                               goto out;
                        } else if (fault & VM_FAULT_SIGBUS) {
                                err = -EACCES;
                                goto out;

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index d8b1ff6..18bce18 100644 (file)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -873,6 +873,8 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
                if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
                             VM_FAULT_HWPOISON_LARGE))
                        do_sigbus(regs, error_code, address, fault);
+               else if (fault & VM_FAULT_SIGSEGV)
+                       bad_area_nosemaphore(regs, error_code, address);
                else
                        BUG();
        }

diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 70fa7bc..3827833 100644 (file)
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -117,6 +117,8 @@ good_area:
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
+               else if (fault & VM_FAULT_SIGSEGV)
+                       goto bad_area;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();

diff --git a/include/linux/mm.h b/include/linux/mm.h
index fb117eb..2d03dca 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -896,6 +896,7 @@ static inline int page_mapped(struct page *page)
 #define VM_FAULT_WRITE 0x0008  /* Special case for get_user_pages */
 #define VM_FAULT_HWPOISON 0x0010       /* Hit poisoned small page */
 #define VM_FAULT_HWPOISON_LARGE 0x0020  /* Hit poisoned large page. Index encoded in upper bits */
+#define VM_FAULT_SIGSEGV 0x0040
 
 #define VM_FAULT_NOPAGE        0x0100  /* ->fault installed the pte, not return page */
 #define VM_FAULT_LOCKED        0x0200  /* ->fault locked the returned page */
@@ -903,8 +904,8 @@ static inline int page_mapped(struct page *page)
 
 #define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
 
-#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | \
-                        VM_FAULT_HWPOISON_LARGE)
+#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
+                        VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)
 
 /* Encode hstate index for a hwpoisoned large page */
 #define VM_FAULT_SET_HINDEX(x) ((x) << 12)

diff --git a/mm/ksm.c b/mm/ksm.c
index effff4e..c615794 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -380,7 +380,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
                else
                        ret = VM_FAULT_WRITE;
                put_page(page);
-       } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_OOM)));
+       } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | VM_FAULT_OOM)));
        /*
         * We must loop because handle_mm_fault() may back out if there's
         * any difficulty e.g. if pte accessed bit gets updated concurrently.

diff --git a/mm/memory.c b/mm/memory.c
index c2ec754..5b05dce 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1861,7 +1861,8 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                                                else
                                                        return -EFAULT;
                                        }
-                                       if (ret & VM_FAULT_SIGBUS)
+                                       if (ret & (VM_FAULT_SIGBUS |
+                                                  VM_FAULT_SIGSEGV))
                                                return i ? i : -EFAULT;
                                        BUG();
                                }
@@ -1971,7 +1972,7 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
                        return -ENOMEM;
                if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
                        return -EHWPOISON;
-               if (ret & VM_FAULT_SIGBUS)
+               if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
                        return -EFAULT;
                BUG();
        }