{"schema":"threatline.record/2","record":{"id":"CVE-2026-93287","aliases":[],"summary":"i2c: smbus: reject oversized block transfers in the common path","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: smbus: reject oversized block transfers in the common path\n\nThe SMBus block transfer length data->block[0] is validated in\ni2c_smbus_xfer_emulated() but that check runs too late for tracepoints\nand is skipped entirely when the adapter provides a native smbus_xfer\nimplementation. This allows user-controlled oversized block lengths to\nreach tracepoint memcpy calls and driver callbacks unchecked.\n\nAdd an early validation in __i2c_smbus_xfer() that rejects block\ntransfers whose caller-supplied length is zero or exceeds\nI2C_SMBUS_BLOCK_MAX before any tracepoint fires or driver callback\nruns. data->block[0] is filled in by the device on SMBus block reads,\nso the check is scoped to operations where the length is actually\nsupplied by the caller. This is consistent with the existing -EINVAL\nconvention in the emulated path and protects all downstream consumers\nat once: the smbus_write tracepoint, all native smbus_xfer driver\nimplementations, and the emulated path.\n\nTwo distinct bugs are fixed by this change:\n\nBug 1: smbus_write tracepoint OOB (include/trace/events/smbus.h)\n  trace_smbus_write() fires before any validation and copies\n  data->block[0]+1 bytes into a 34-byte event buffer. With\n  block[0]=0xfe the tracepoint copies 255 bytes, overflowing by 221.\n\n BUG: KASAN: stack-out-of-bounds in trace_event_raw_event_smbus_write+0x27c/0x530\n Read of size 255 at addr ffff88800d98fcf8 by task poc_smbus/91\n Call Trace:\n  <TASK>\n  __asan_memcpy+0x23/0x80\n  trace_event_raw_event_smbus_write+0x27c/0x530\n  __i2c_smbus_xfer+0x43a/0xa40\n  i2c_smbus_xfer+0x19e/0x340\n  i2cdev_ioctl_smbus+0x38f/0x7f0\n  i2cdev_ioctl+0x35e/0x680\n  __x64_sys_ioctl+0x147/0x1e0\n  do_syscall_64+0xcf/0x15a0\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n  </TASK>\n\nBug 2: i2c-stub I2C_SMBUS_I2C_BLOCK_DATA OOB (drivers/i2c/i2c-stub.c)\n  stub_xfer() implements .smbus_xfer directly and only clamps\n  block[0] against 256-command, not I2C_SMBUS_BLOCK_MAX. With\n  block[0]=0xff and command=0 the loop accesses block[1+i] for\n  i up to 254, far past the 34-byte union.\n\n UBSAN: array-index-out-of-bounds in drivers/i2c/i2c-stub.c:223:44\n index 34 is out of range for type '__u8 [34]'\n Call Trace:\n  <TASK>\n  __ubsan_handle_out_of_bounds+0xd7/0x120\n  stub_xfer+0x1971/0x198f [i2c_stub]\n  __i2c_smbus_xfer+0x306/0xa40\n  i2c_smbus_xfer+0x19e/0x340\n  i2cdev_ioctl_smbus+0x38f/0x7f0\n  i2cdev_ioctl+0x35e/0x680\n  __x64_sys_ioctl+0x147/0x1e0\n  do_syscall_64+0xcf/0x15a0\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n  </TASK>\n\nBoth traces reproduced on v7.0-rc6+i2c/for-current with KASAN+UBSAN.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"Linux","vendor":"Linux","versions":[{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"856dffcc097b3d8ed45a643ebda07cb92968cb33","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"356875e33f2c6d2061a02c9dec1a1e639d265a55","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"72ca5e0b8b7a62615758f8871c34d61616c2dc8b","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"df077253f6405d67ad087538e495ef32a05717b7","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"f09edffba97d37b1fdff5f818a9a45f8a98ac171","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"c4b478bc50b7ca9865e237909941253a0f7111a2","status":"affected","versionType":"git"},{"version":"4710317891e4824ce1510a6b5066abbd3e917750","lessThan":"3051cd060fa496df42954291fa2306ed2eab4ecc","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"Linux","vendor":"Linux","versions":[{"version":"2.6.33","status":"affected"},{"version":"0","lessThan":"2.6.33","status":"unaffected","versionType":"semver"},{"version":"5.10.271","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.222","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"Linux","ecosystem":null},"version":"856dffcc097b3d8ed45a643ebda07cb92968cb33","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"Linux","ecosystem":null},"version":"356875e33f2c6d2061a02c9dec1a1e639d265a55","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"Linux","ecosystem":null},"version":"72ca5e0b8b7a62615758f8871c34d61616c2dc8b","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","source_modified_at":"2026-10-03T10:57:13.466Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"Linux","ecosystem":null},"version":"3051cd060fa496df42954291fa2306ed2eab4ecc","basis":"first unaffected version stated in the CVE record"}],"cvss":7.8,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00129,"percentile":0.02329,"score_date":"2026-10-23"},"published_at":"2026-09-24T16:02:11.296Z","modified_at":"2026-10-03T10:57:13.466Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-93287","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-03T10:57:13.466Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-93287","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/856dffcc097b3d8ed45a643ebda07cb92968cb33"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/356875e33f2c6d2061a02c9dec1a1e639d265a55"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/72ca5e0b8b7a62615758f8871c34d61616c2dc8b"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/df077253f6405d67ad087538e495ef32a05717b7"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/f09edffba97d37b1fdff5f818a9a45f8a98ac171"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/c4b478bc50b7ca9865e237909941253a0f7111a2"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/3051cd060fa496df42954291fa2306ed2eab4ecc"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-03T10:57:13.466Z","content_hash":"f10b37c4b1cfdad9a1417153ea2b174f6e7119a5a642ef1fa5c2a7382d62c3bf"}}