From a070aec875a39a46d34d37b8f5d4ed596b738ed4 Mon Sep 17 00:00:00 2001 From: Anmol Jain Date: Thu, 29 May 2025 20:00:03 +0000 Subject: [PATCH] ALSA: usb-audio: Fix out of bounds reads when finding clock sources MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-46530 cve CVE-2024-53150 commit-author Takashi Iwai commit a3dd4d63eeb452cfb064a13862fb376ab108f6a6 The current USB-audio driver code doesn't check bLength of each descriptor at traversing for clock descriptors. That is, when a device provides a bogus descriptor with a shorter bLength, the driver might hit out-of-bounds reads. For addressing it, this patch adds sanity checks to the validator functions for the clock descriptor traversal. When the descriptor length is shorter than expected, it's skipped in the loop. For the clock source and clock multiplier descriptors, we can just check bLength against the sizeof() of each descriptor type. OTOH, the clock selector descriptor of UAC2 and UAC3 has an array of bNrInPins elements and two more fields at its tail, hence those have to be checked in addition to the sizeof() check. Reported-by: Benoît Sevens Cc: Link: https://lore.kernel.org/20241121140613.3651-1-bsevens@google.com Link: https://patch.msgid.link/20241125144629.20757-1-tiwai@suse.de Signed-off-by: Takashi Iwai (cherry picked from commit a3dd4d63eeb452cfb064a13862fb376ab108f6a6) Signed-off-by: Anmol Jain --- sound/usb/clock.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/sound/usb/clock.c b/sound/usb/clock.c index 33db334e65566..4bae57cdb5dd2 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -36,6 +36,12 @@ union uac23_clock_multiplier_desc { struct uac_clock_multiplier_descriptor v3; }; +/* check whether the descriptor bLength has the minimal length */ +#define DESC_LENGTH_CHECK(p, proto) \ + ((proto) == UAC_VERSION_3 ? \ + ((p)->v3.bLength >= sizeof((p)->v3)) : \ + ((p)->v2.bLength >= sizeof((p)->v2))) + #define GET_VAL(p, proto, field) \ ((proto) == UAC_VERSION_3 ? (p)->v3.field : (p)->v2.field) @@ -58,6 +64,8 @@ static bool validate_clock_source(void *p, int id, int proto) { union uac23_clock_source_desc *cs = p; + if (!DESC_LENGTH_CHECK(cs, proto)) + return false; return GET_VAL(cs, proto, bClockID) == id; } @@ -65,13 +73,27 @@ static bool validate_clock_selector(void *p, int id, int proto) { union uac23_clock_selector_desc *cs = p; - return GET_VAL(cs, proto, bClockID) == id; + if (!DESC_LENGTH_CHECK(cs, proto)) + return false; + if (GET_VAL(cs, proto, bClockID) != id) + return false; + /* additional length check for baCSourceID array (in bNrInPins size) + * and two more fields (which sizes depend on the protocol) + */ + if (proto == UAC_VERSION_3) + return cs->v3.bLength >= sizeof(cs->v3) + cs->v3.bNrInPins + + 4 /* bmControls */ + 2 /* wCSelectorDescrStr */; + else + return cs->v2.bLength >= sizeof(cs->v2) + cs->v2.bNrInPins + + 1 /* bmControls */ + 1 /* iClockSelector */; } static bool validate_clock_multiplier(void *p, int id, int proto) { union uac23_clock_multiplier_desc *cs = p; + if (!DESC_LENGTH_CHECK(cs, proto)) + return false; return GET_VAL(cs, proto, bClockID) == id; }