{"id":"CVE-2026-98741","title":"ALSA: ua101: reject mismatched capture/playback packet sizes","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: ua101: reject mismatched capture/playback packet sizes\n\ndetect_usb_format() cross-checks bSubframeSize, bBitResolution and\ntSamFreq between the capture and playba…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < fd3a7bf0d988b0878a1957df150edb35f81db87e","Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < eb0c7fda59cf650076f8ed5b949a6c8441aa3606","Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < 4294fe57048594a9e158b61c967bb7f943cda477","Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < 86f86e6fdedc33c5b8d38b9208b350f8accf57ee","Linux 2.6.34"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:47:26.283Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98741","references":[{"url":"https://git.kernel.org/stable/c/fd3a7bf0d988b0878a1957df150edb35f81db87e"},{"url":"https://git.kernel.org/stable/c/eb0c7fda59cf650076f8ed5b949a6c8441aa3606"},{"url":"https://git.kernel.org/stable/c/4294fe57048594a9e158b61c967bb7f943cda477"},{"url":"https://git.kernel.org/stable/c/86f86e6fdedc33c5b8d38b9208b350f8accf57ee"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.502Z","slug":"CVE-2026-98741","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nALSA: ua101: reject mismatched capture/playback packet sizes\n\ndetect_usb_format() cross-checks bSubframeSize, bBitResolution and\ntSamFreq between the capture and playback interfaces, but never relates\nthe two endpoints' wMaxPacketSize and bNrChannels.  Each playback URB\ngets a buffer of ua->playback.max_packet_bytes, while the number of\nbytes written into it is derived from the capture stream:\ncapture_urb_complete() computes frames from the received capture packet\nand capture.frame_bytes, and start_usb_playback() and playback_work()\nmultiply that by playback.frame_bytes.\n\nA device declaring a large capture wMaxPacketSize with few capture\nchannels and a small playback wMaxPacketSize with many playback channels\ntherefore memset()s and memcpy()s past the end of the playback buffer,\nin open() of the PCM node the driver registers during probe.\nusb_submit_urb() rejects the over-long iso_frame_desc[0].length with\n-EMSGSIZE, but only after the write.\n\nReject such descriptors at probe time.  Genuine UA-101/UA-1000 hardware\ndeclares proportional packet sizes and is unaffected.\n\n  BUG: KASAN: slab-out-of-bounds in start_usb_playback (sound/usb/misc/ua101.c:586)\n  Write of size 2048 at addr ffff8881098f3c00 by task exploit/5021\n  Call Trace:\n   __asan_memset (mm/kasan/shadow.c:84)\n   start_usb_playback (sound/usb/misc/ua101.c:586)\n   playback_pcm_open (sound/usb/misc/ua101.c:679)\n   snd_pcm_open_substream (sound/core/pcm_native.c:2829)\n   snd_pcm_open (sound/core/pcm_native.c:2865 sound/core/pcm_native.c:2932)\n   snd_pcm_playback_open (sound/core/pcm_native.c:2891)\n   snd_open (sound/core/sound.c:166)\n   chrdev_open (fs/char_dev.c:411)\n   do_dentry_open (fs/open.c:996)\n   vfs_open (fs/open.c:1101)\n   path_openat (fs/namei.c:4837 fs/namei.c:5000)\n   do_file_open (fs/namei.c:5029)\n   do_sys_openat2 (fs/open.c:1417)\n   __x64_sys_openat (fs/open.c:1423 fs/open.c:1439 fs/open.c:1434)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\n  The buggy address belongs to the object at ffff8881098f3c00\n   which belongs to the cache kmalloc-192 of size 192\n  The buggy address is located 0 bytes inside of\n   allocated 168-byte region [ffff8881098f3c00, ffff8881098f3ca8)\n\n## Affected\n\n- `Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < fd3a7bf0d988b0878a1957df150edb35f81db87e`\n- `Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < eb0c7fda59cf650076f8ed5b949a6c8441aa3606`\n- `Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < 4294fe57048594a9e158b61c967bb7f943cda477`\n- `Linux >= 63978ab3e3e963db28093b53bb4598f2702e1ad7 < 86f86e6fdedc33c5b8d38b9208b350f8accf57ee`\n- `Linux 2.6.34`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}