Commit 8b53b756 authored by Prakash Gupta's avatar Prakash Gupta Committed by Greg Kroah-Hartman

mm/cma_debug.c: fix stack corruption due to sprintf usage

commit da094e42 upstream.

name[] in cma_debugfs_add_one() can only accommodate 16 chars including
NULL to store sprintf output.  It's common for cma device name to be
larger than 15 chars.  This can cause stack corrpution.  If the gcc
stack protector is turned on, this can cause a panic due to stack
corruption.

Below is one example trace:

  Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
  ffffff8e69a75730
  Call trace:
     dump_backtrace+0x0/0x2c4
     show_stack+0x20/0x28
     dump_stack+0xb8/0xf4
     panic+0x154/0x2b0
     print_tainted+0x0/0xc0
     cma_debugfs_init+0x274/0x290
     do_one_initcall+0x5c/0x168
     kernel_init_freeable+0x1c8/0x280

Fix the short sprintf buffer in cma_debugfs_add_one() by using
scnprintf() instead of sprintf().

Link: http://lkml.kernel.org/r/1502446217-21840-1-git-send-email-guptap@codeaurora.org
Fixes: f318dd08 ("cma: Store a name in the cma structure")
Signed-off-by: default avatarPrakash Gupta <guptap@codeaurora.org>
Acked-by: default avatarLaura Abbott <labbott@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 76e8fe02
...@@ -167,7 +167,7 @@ static void cma_debugfs_add_one(struct cma *cma, int idx) ...@@ -167,7 +167,7 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
char name[16]; char name[16];
int u32s; int u32s;
sprintf(name, "cma-%s", cma->name); scnprintf(name, sizeof(name), "cma-%s", cma->name);
tmp = debugfs_create_dir(name, cma_debugfs_root); tmp = debugfs_create_dir(name, cma_debugfs_root);
......
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