Commit 7fc6798d authored by Kees Cook's avatar Kees Cook Committed by Luo Gengkun
Browse files

ALSA: seq: Fix function prototype mismatch in snd_seq_expand_var_event 

mainline inclusion
from mainline-v6.1-rc7
commit 05530ef7
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRDZ
CVE: CVE-2022-48994

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=05530ef7cf7c7d700f6753f058999b1b5099a026



--------------------------------

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.

seq_copy_in_user() and seq_copy_in_kernel() did not have prototypes
matching snd_seq_dump_func_t. Adjust this and remove the casts. There
are not resulting binary output differences.

This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.

Reported-by: default avatarkernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com


Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: alsa-devel@alsa-project.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221118232346.never.380-kees@kernel.org


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarLuo Gengkun <luogengkun2@huawei.com>
parent 1b77b8cd

sound/core/seq/seq_memory.c

+7 −4
Original line number Diff line number Diff line
@@ -126,15 +126,19 @@ EXPORT_SYMBOL(snd_seq_dump_var_event); 
 * expand the variable length event to linear buffer space.

 */



static int seq_copy_in_kernel(char **bufptr, const void *src, int size)

static int seq_copy_in_kernel(void *ptr, void *src, int size)

{

	char **bufptr = ptr;



	memcpy(*bufptr, src, size);

	*bufptr += size;

	return 0;

}



static int seq_copy_in_user(char __user **bufptr, const void *src, int size)

static int seq_copy_in_user(void *ptr, void *src, int size)

{

	char __user **bufptr = ptr;



	if (copy_to_user(*bufptr, src, size))

		return -EFAULT;

	*bufptr += size;
@@ -163,8 +167,7 @@ int snd_seq_expand_var_event(const struct snd_seq_event *event, int count, char 
		return newlen;

	}

	err = snd_seq_dump_var_event(event,

				     in_kernel ? (snd_seq_dump_func_t)seq_copy_in_kernel :

				     (snd_seq_dump_func_t)seq_copy_in_user,

				     in_kernel ? seq_copy_in_kernel : seq_copy_in_user,

				     &buf);

	return err < 0 ? err : newlen;

}