{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-39486","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-06-25T14:23:23.747Z","datePublished":"2024-07-06T09:25:21.514Z","dateUpdated":"2026-08-05T11:33:38.384Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:33:38.384Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/drm_file: Fix pid refcounting race\n\n<maarten.lankhorst@linux.intel.com>, Maxime Ripard\n<mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>\n\nfilp->pid is supposed to be a refcounted pointer; however, before this\npatch, drm_file_update_pid() only increments the refcount of a struct\npid after storing a pointer to it in filp->pid and dropping the\ndev->filelist_mutex, making the following race possible:\n\nprocess A               process B\n=========               =========\n                        begin drm_file_update_pid\n                        mutex_lock(&dev->filelist_mutex)\n                        rcu_replace_pointer(filp->pid, <pid B>, 1)\n                        mutex_unlock(&dev->filelist_mutex)\nbegin drm_file_update_pid\nmutex_lock(&dev->filelist_mutex)\nrcu_replace_pointer(filp->pid, <pid A>, 1)\nmutex_unlock(&dev->filelist_mutex)\nget_pid(<pid A>)\nsynchronize_rcu()\nput_pid(<pid B>)   *** pid B reaches refcount 0 and is freed here ***\n                        get_pid(<pid B>)   *** UAF ***\n                        synchronize_rcu()\n                        put_pid(<pid A>)\n\nAs far as I know, this race can only occur with CONFIG_PREEMPT_RCU=y\nbecause it requires RCU to detect a quiescent state in code that is not\nexplicitly calling into the scheduler.\n\nThis race leads to use-after-free of a \"struct pid\".\nIt is probably somewhat hard to hit because process A has to pass\nthrough a synchronize_rcu() operation while process B is between\nmutex_unlock() and get_pid().\n\nFix it by ensuring that by the time a pointer to the current task's pid\nis stored in the file, an extra reference to the pid has been taken.\n\nThis fix also removes the condition for synchronize_rcu(); I think\nthat optimization is unnecessary complexity, since in that case we\nwould usually have bailed out on the lockless check above."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable code is reached through `ioctl()` on a DRM device node (`/dev/dri/card*` or `/dev/dri/renderD*`), which requires local access to the system. There is no network or remote path into `drm_ioctl_kernel()`.\nAC:L - The attacker owns both sides of the race — `fork()`/SCM_RIGHTS gives two processes sharing one `struct file`, and alternating ioctls from the two tgids re-enter `drm_file_update_pid()`'s update path on demand, so the race can be driven in a tight loop with attacker-controlled CPU pinning and preemption pressure. The required `CONFIG_PREEMPT_RCU` is the default on Android, mainstream distro `PREEMPT_DYNAMIC` kernels, and PREEMPT_RT, so it is not a rare configuration.\nPR:L - Only an unprivileged local user is needed: `drm_file_update_pid()` runs before `drm_ioctl_permit()`, so no DRM_AUTH, DRM_MASTER, or DRM_ROOT_ONLY check applies, and render nodes are routinely accessible to ordinary users (Android apps, desktop `render`/`video` group members) or via a DRM fd passed into a sandbox by the compositor.\nUI:N - The attacker performs the entire sequence itself — open the DRM node, fork, and issue concurrent ioctls. No victim process needs to act or be in any particular state.\nS:U - The use-after-free corrupts kernel slab memory within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed by the flaw itself.\nC:H - The freed `struct pid` can be reallocated with attacker-sprayed data and is subsequently read by `put_pid()` (`pid->numbers[pid->level].ns`) and by pid-lookup paths, giving a use-after-free read primitive that can be leveraged to disclose arbitrary kernel memory.\nI:H - `get_pid()` performs a refcount increment into freed slab memory, and the stale reference later drives `refcount_dec_and_test()` plus `kmem_cache_free()` on a possibly reallocated object — a UAF write and double-free on a core object, which is a well-established primitive for heap grooming and local privilege escalation.\nA:H - The use-after-free on `struct pid` corrupts the pid slab cache and triggers refcount underflow warnings, invalid frees, and kernel oops/panic, and the race can be re-triggered repeatedly by an unprivileged process."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_file.c"],"versions":[{"version":"031ddd28008971cce0b5626379b910d0a05fb4dd","lessThan":"16682588ead4a593cf1aebb33b36df4d1e9e4ffa","status":"affected","versionType":"git"},{"version":"1c7a387ffef894b1ab3942f0482dac7a6e0a909c","lessThan":"0acce2a5c619ef1abdee783d7fea5eac78ce4844","status":"affected","versionType":"git"},{"version":"1c7a387ffef894b1ab3942f0482dac7a6e0a909c","lessThan":"4f2a129b33a2054e62273edd5a051c34c08d96e9","status":"affected","versionType":"git"},{"version":"6.6.9","lessThan":"6.6.37","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_file.c"],"versions":[{"version":"6.7","status":"affected"},{"version":"0","lessThan":"6.7","status":"unaffected","versionType":"semver"},{"version":"6.6.37","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.9.8","lessThanOrEqual":"6.9.*","status":"unaffected","versionType":"semver"},{"version":"6.10","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.9","versionEndExcluding":"6.6.37"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.9.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.10"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/16682588ead4a593cf1aebb33b36df4d1e9e4ffa"},{"url":"https://git.kernel.org/stable/c/0acce2a5c619ef1abdee783d7fea5eac78ce4844"},{"url":"https://git.kernel.org/stable/c/4f2a129b33a2054e62273edd5a051c34c08d96e9"}],"title":"drm/drm_file: Fix pid refcounting race","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-07-08T15:13:18.216624Z","id":"CVE-2024-39486","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-07-08T15:13:34.330Z"}},{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-02T04:26:15.689Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/16682588ead4a593cf1aebb33b36df4d1e9e4ffa","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/0acce2a5c619ef1abdee783d7fea5eac78ce4844","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/4f2a129b33a2054e62273edd5a051c34c08d96e9","tags":["x_transferred"]}]}]}}