RISC-V: kexec: Fix memory leak of fdt buffer

commit 96df59b1ae23f5c11698c3c2159aeb2ecd4944a4 upstream.

This is reported by kmemleak detector:

unreferenced object 0xff60000082864000 (size 9588):
  comm "kexec", pid 146, jiffies 4294900634 (age 64.788s)
  hex dump (first 32 bytes):
    d0 0d fe ed 00 00 12 ed 00 00 00 48 00 00 11 40  ...........H...@
    00 00 00 28 00 00 00 11 00 00 00 02 00 00 00 00  ...(............
  backtrace:
    [<00000000f95b17c4>] kmemleak_alloc+0x34/0x3e
    [<00000000b9ec8e3e>] kmalloc_order+0x9c/0xc4
    [<00000000a95cf02e>] kmalloc_order_trace+0x34/0xb6
    [<00000000f01e68b4>] __kmalloc+0x5c2/0x62a
    [<000000002bd497b2>] kvmalloc_node+0x66/0xd6
    [<00000000906542fa>] of_kexec_alloc_and_setup_fdt+0xa6/0x6ea
    [<00000000e1166bde>] elf_kexec_load+0x206/0x4ec
    [<0000000036548e09>] kexec_image_load_default+0x40/0x4c
    [<0000000079fbe1b4>] sys_kexec_file_load+0x1c4/0x322
    [<0000000040c62c03>] ret_from_syscall+0x0/0x2

In elf_kexec_load(), a buffer is allocated via kvmalloc() to store fdt.
While it's not freed back to system when kexec kernel is reloaded or
unloaded.  Then memory leak is caused.  Fix it by introducing riscv
specific function arch_kimage_file_post_load_cleanup(), and freeing the
buffer there.

Fixes: 6261586e0c91 ("RISC-V: Add kexec_file support")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Liao Chang <liaochang1@huawei.com>
Link: https://lore.kernel.org/r/20221104095658.141222-1-lihuafei1@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h
index eee260e8ab308e8a033995082e1119df4739eeb3..2b56769cb530cbcc164206a1fe0361a6a9fa013f 100644 (file)
--- a/arch/riscv/include/asm/kexec.h
+++ b/arch/riscv/include/asm/kexec.h
@@ -39,6 +39,7 @@ crash_setup_regs(struct pt_regs *newregs,
 #define ARCH_HAS_KIMAGE_ARCH
 
 struct kimage_arch {
+       void *fdt; /* For CONFIG_KEXEC_FILE */
        unsigned long fdt_addr;
 };
 
@@ -62,6 +63,10 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
                                     const Elf_Shdr *relsec,
                                     const Elf_Shdr *symtab);
 #define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
+
+struct kimage;
+int arch_kimage_file_post_load_cleanup(struct kimage *image);
+#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup
 #endif
 
 #endif

diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
index 0cb94992c15b32a852716ca877d95b5f14f63c6f..ff30fcb43f47ac100986060d253da3b07d73a611 100644 (file)
--- a/arch/riscv/kernel/elf_kexec.c
+++ b/arch/riscv/kernel/elf_kexec.c
@@ -21,6 +21,14 @@
 #include <linux/memblock.h>
 #include <asm/setup.h>
 
+int arch_kimage_file_post_load_cleanup(struct kimage *image)
+{
+       kvfree(image->arch.fdt);
+       image->arch.fdt = NULL;
+
+       return kexec_image_post_load_cleanup_default(image);
+}
+
 static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
                                struct kexec_elf_info *elf_info, unsigned long old_pbase,
                                unsigned long new_pbase)
@@ -298,6 +306,8 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
                pr_err("Error add DTB kbuf ret=%d\n", ret);
                goto out_free_fdt;
        }
+       /* Cache the fdt buffer address for memory cleanup */
+       image->arch.fdt = fdt;
        pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem);
        goto out;