{"id":"CVE-2026-45878","title":"drm/amdkfd: Fix watch_id bounds checking in debug address watch v2","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdkfd: Fix watch_id bounds checking in debug address watch v2\n\nThe address watch clear code receives watch_id as an unsigned value\n(u32), but some helper functions…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 971bf8e61e9b4abaacf9b35eaf76ec222758f9d6","Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488","Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 2b36c0c1bcbbe15f6cfa9652084b3124c835a150","Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 3c38a0f07aa2bfef2b219b1f045534ad93f85afd","Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 5a19302cab5cec7ae7f1a60c619951e6c17d8742","Linux 6.5"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:18:15.974841Z"},"published":"2026-05-27","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:20:46.204Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-45878","references":[{"url":"https://git.kernel.org/stable/c/971bf8e61e9b4abaacf9b35eaf76ec222758f9d6"},{"url":"https://git.kernel.org/stable/c/a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488"},{"url":"https://git.kernel.org/stable/c/2b36c0c1bcbbe15f6cfa9652084b3124c835a150"},{"url":"https://git.kernel.org/stable/c/3c38a0f07aa2bfef2b219b1f045534ad93f85afd"},{"url":"https://git.kernel.org/stable/c/5a19302cab5cec7ae7f1a60c619951e6c17d8742"}],"tags":["cve.org"],"epss":0.00182,"epssPercentile":0.07282,"ingestedAt":"2026-10-16T17:24:46.699Z","slug":"CVE-2026-45878","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdkfd: Fix watch_id bounds checking in debug address watch v2\n\nThe address watch clear code receives watch_id as an unsigned value\n(u32), but some helper functions were using a signed int and checked\nbits by shifting with watch_id.\n\nIf a very large watch_id is passed from userspace, it can be converted\nto a negative value.  This can cause invalid shifts and may access\nmemory outside the watch_points array.\n\ndrm/amdkfd: Fix watch_id bounds checking in debug address watch v2\n\nFix this by checking that watch_id is within MAX_WATCH_ADDRESSES before\nusing it.  Also use BIT(watch_id) to test and clear bits safely.\n\nThis keeps the behavior unchanged for valid watch IDs and avoids\nundefined behavior for invalid ones.\n\nFixes the below:\ndrivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_debug.c:448\nkfd_dbg_trap_clear_dev_address_watch() error: buffer overflow\n'pdd->watch_points' 4 <= u32max user_rl='0-3,2147483648-u32max' uncapped\n\ndrivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_debug.c\n    433 int kfd_dbg_trap_clear_dev_address_watch(struct kfd_process_device *pdd,\n    434                                         uint32_t watch_id)\n    435 {\n    436         int r;\n    437\n    438         if (!kfd_dbg_owns_dev_watch_id(pdd, watch_id))\n\nkfd_dbg_owns_dev_watch_id() doesn't check for negative values so if\nwatch_id is larger than INT_MAX it leads to a buffer overflow.\n(Negative shifts are undefined).\n\n    439                 return -EINVAL;\n    440\n    441         if (!pdd->dev->kfd->shared_resources.enable_mes) {\n    442                 r = debug_lock_and_unmap(pdd->dev->dqm);\n    443                 if (r)\n    444                         return r;\n    445         }\n    446\n    447         amdgpu_gfx_off_ctrl(pdd->dev->adev, false);\n--> 448         pdd->watch_points[watch_id] = pdd->dev->kfd2kgd->clear_address_watch(\n    449                                                         pdd->dev->adev,\n    450                                                         watch_id);\n\nv2: (as per, Jonathan Kim)\n - Add early watch_id >= MAX_WATCH_ADDRESSES validation in the set path to\n   match the clear path.\n - Drop the redundant bounds check in kfd_dbg_owns_dev_watch_id().\n\n## Affected\n\n- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 971bf8e61e9b4abaacf9b35eaf76ec222758f9d6`\n- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < a0d367e13db63a6ed76ee0d0a8c3a58c1fa98488`\n- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 2b36c0c1bcbbe15f6cfa9652084b3124c835a150`\n- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 3c38a0f07aa2bfef2b219b1f045534ad93f85afd`\n- `Linux >= e0f85f4690d089cc1a60337decafb1acf7eec45e < 5a19302cab5cec7ae7f1a60c619951e6c17d8742`\n- `Linux 6.5`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}