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

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 <[email protected]> know about it.

From: Prakash Gupta <[email protected]>
Date: Fri, 18 Aug 2017 15:16:21 -0700
Subject: mm/cma_debug.c: fix stack corruption due to sprintf usage

From: Prakash Gupta <[email protected]>

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().

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

@@ -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 [email protected] are

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