From: Lucy Thrun lucy.thrun@digital-rabbithole.de
[ Upstream commit a409c60111e6bb98fcabab2aeaa069daa9434ca0 ]
The 'sprintf' call in 'add_tuning_control' may exceed the 44-byte buffer if either string argument is too long. This triggers a compiler warning. Replaced 'sprintf' with 'snprintf' to limit string lengths to prevent overflow.
Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202506100642.95jpuMY1-lkp@intel.com/ Signed-off-by: Lucy Thrun lucy.thrun@digital-rabbithole.de Link: https://patch.msgid.link/20250610175012.918-3-lucy.thrun@digital-rabbithole.... Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
**Backport Status: YES**
This commit should be backported to stable kernel trees for the following reasons:
1. **Fixes a real security vulnerability**: The commit fixes a buffer overflow vulnerability in the `add_tuning_control` function. The sprintf call could overflow the 44-byte `namestr` buffer (defined as `char namestr[SNDRV_CTL_ELEM_ID_NAME_MAXLEN]` where `SNDRV_CTL_ELEM_ID_NAME_MAXLEN` is 44).
2. **Long-standing bug**: The vulnerable code was introduced in 2012 (commit 44f0c9782cc6a), meaning this buffer overflow has existed in the kernel for over a decade, affecting many stable kernel versions.
3. **Simple and contained fix**: The fix is minimal - it simply replaces `sprintf` with `snprintf` on a single line: ```c - sprintf(namestr, "%s %s Volume", name, dirstr[dir]); + snprintf(namestr, sizeof(namestr), "%s %s Volume", name, dirstr[dir]); ```
4. **Low risk of regression**: The change is straightforward and only adds bounds checking. It doesn't change any logic or behavior when strings fit within the buffer.
5. **Detected by automated testing**: The issue was caught by the kernel test robot, indicating it's a real compiler warning that should be addressed.
6. **Potential for exploitation**: While the tuning control names like "Wedge Angle", "SVM Level", and "EQ Band0-9" are relatively short, combined with "Playback" or "Capture" and " Volume", they could theoretically overflow the 44-byte buffer. For example: "EQ Band9" (8) + " " (1) + "Playback" (8) + " Volume" (7) = 24 bytes, which is safe, but the vulnerability exists if longer names were added in the future.
7. **Affects user-facing functionality**: This is in the ALSA HD Audio driver for Creative CA0132 sound cards, which are used by end users, making it important to fix in stable kernels.
The fix follows stable kernel rules perfectly: it's a minimal change that fixes an important bug without introducing new features or architectural changes.
sound/pci/hda/patch_ca0132.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c index 748a3c40966e..c19164089ae4 100644 --- a/sound/pci/hda/patch_ca0132.c +++ b/sound/pci/hda/patch_ca0132.c @@ -4399,7 +4399,7 @@ static int add_tuning_control(struct hda_codec *codec, } knew.private_value = HDA_COMPOSE_AMP_VAL(nid, 1, 0, type); - sprintf(namestr, "%s %s Volume", name, dirstr[dir]); + snprintf(namestr, sizeof(namestr), "%s %s Volume", name, dirstr[dir]); return snd_hda_ctl_add(codec, nid, snd_ctl_new1(&knew, codec)); }