4.12-stable review patch. If anyone has any objections, please let me know.
------------------ 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(). Link: http://lkml.kernel.org/r/[email protected] Fixes: f318dd083c81 ("cma: Store a name in the cma structure") Signed-off-by: Prakash Gupta <[email protected]> Acked-by: Laura Abbott <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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);
