Patch "mm/cma_debug.c: fix stack corruption due to sprintf usage" has been added to the 4.12-stable tree

Patch "mm/cma_debug.c: fix stack corruption due to sprintf usage" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mm-cma_debug.c-fix-stack-corruption-due-to-sprintf-usage.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From da094e42848e3c36feaa3b5271e53983fd45424f Mon Sep 17 00:00:00 2001
From: Prakash Gupta <guptap@codeaurora.org>
Date: Fri, 18 Aug 2017 15:16:21 -0700
Subject: mm/cma_debug.c: fix stack corruption due to sprintf usage

From: Prakash Gupta <guptap@codeaurora.org>

commit da094e42848e3c36feaa3b5271e53983fd45424f 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: f318dd083c81 ("cma: Store a name in the cma structure")
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/cma_debug.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -167,7 +167,7 @@ static void cma_debugfs_add_one(struct c
 	char name[16];
 	int u32s;
 
-	sprintf(name, "cma-%s", cma->name);
+	scnprintf(name, sizeof(name), "cma-%s", cma->name);
 
 	tmp = debugfs_create_dir(name, cma_debugfs_root);
 


Patches currently in stable-queue which might be from guptap@codeaurora.org are

queue-4.12/mm-cma_debug.c-fix-stack-corruption-due-to-sprintf-usage.patch