pipe: reject F_SETPIPE_SZ with size over UINT_MAX

A pipe's size is represented as an 'unsigned int'.  As expected, writing a
value greater than UINT_MAX to /proc/sys/fs/pipe-max-size fails with
EINVAL.  However, the F_SETPIPE_SZ fcntl silently truncates such values to
32 bits, rather than failing with EINVAL as expected.  (It *does* fail
with EINVAL for values above (1 << 31) but <= UINT_MAX.)

Fix this by moving the check against UINT_MAX into round_pipe_size() which
is called in both cases.

Link: http://lkml.kernel.org/r/20180111052902.14409-6-ebiggers3@gmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/pipe.c b/fs/pipe.c
index 46c30ac..817393d 100644 (file)
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1020,10 +1020,13 @@ const struct file_operations pipefifo_fops = {
  * Currently we rely on the pipe array holding a power-of-2 number
  * of pages. Returns 0 on error.
  */
-unsigned int round_pipe_size(unsigned int size)
+unsigned int round_pipe_size(unsigned long size)
 {
        unsigned long nr_pages;
 
+       if (size > UINT_MAX)
+               return 0;
+
        /* Minimum pipe size, as required by POSIX */
        if (size < PAGE_SIZE)
                size = PAGE_SIZE;

diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 5028bd4..5a3bb3b 100644 (file)
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -190,6 +190,6 @@ long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
 struct pipe_inode_info *get_pipe_info(struct file *file);
 
 int create_pipe_files(struct file **, int);
-unsigned int round_pipe_size(unsigned int size);
+unsigned int round_pipe_size(unsigned long size);
 
 #endif

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 59f09ea..f98f28c 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2623,9 +2623,6 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
        if (write) {
                unsigned int val;
 
-               if (*lvalp > UINT_MAX)
-                       return -EINVAL;
-
                val = round_pipe_size(*lvalp);
                if (val == 0)
                        return -EINVAL;