{"id":"CVE-2022-49768","state":"PUBLISHED","title":"9p: trans_fd/p9_conn_cancel: drop client lock earlier","description":"In the Linux kernel, the following vulnerability has been resolved:\n\n9p: trans_fd/p9_conn_cancel: drop client lock earlier\n\nsyzbot reported a double-lock here and we no longer need this\nlock after requests have been moved off to local list:\njust drop the lock earlier.","publishedAt":"2025-05-01T14:09:06.864Z","updatedAt":"2026-08-05T08:56:16.608Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux 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trans_fd/p9_conn_cancel: drop client lock earlier","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\n9p: trans_fd/p9_conn_cancel: drop client lock earlier\n\nsyzbot reported a double-lock here and we no longer need this\nlock after requests have been moved off to local list:\njust drop the lock earlier."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"eb1ca07f4343b4e58b97e792a85d5ba1ba103f5d","status":"affected","lessThan":"82825dbf393f7c7979d462f9609a15bde8092b3f","versionType":"git"},{"version":"4cd195263e420311d31451cc053fde8037f326f1","status":"affected","lessThan":"e3031280fe4eaf61a09e60823331f81f321be8e1","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"fec1406f5e7ab20b71f6d231792b0040e3300aaf","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"96760723aae1b45f733f702abb4333137143909f","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"f14858bc77c567e089965962877ee726ffad0556","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"a4f1a01b2e81378fce9ca528d4d8a049e4b58fcd","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"612c977f5d481f551d03d83d0aef588845c1300c","versionType":"git"},{"version":"9f476d7c540cb57556d3cc7e78704e6cd5100f5f","status":"affected","lessThan":"52f1c45dde9136f964d63a77d19826c8a74e2c7f","versionType":"git"},{"version":"91ca7c5644c370dc5132b1db1aea81416a4b2181","status":"affected","versionType":"git"},{"version":"4.9.127","status":"affected","lessThan":"4.9.334","versionType":"semver"},{"version":"4.14.70","status":"affected","lessThan":"4.14.300","versionType":"semver"},{"version":"4.18.8","status":"affected","lessThan":"4.19","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.19","versionType":"semver"},{"version":"4.9.334","status":"unaffected","lessThanOrEqual":"4.9.*","versionType":"semver"},{"version":"4.14.300","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.267","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.225","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.156","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.80","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.0.10","status":"unaffected","lessThanOrEqual":"6.0.*","versionType":"semver"},{"version":"6.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/9p/trans_fd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/82825dbf393f7c7979d462f9609a15bde8092b3f"},{"url":"https://git.kernel.org/stable/c/e3031280fe4eaf61a09e60823331f81f321be8e1"},{"url":"https://git.kernel.org/stable/c/fec1406f5e7ab20b71f6d231792b0040e3300aaf"},{"url":"https://git.kernel.org/stable/c/96760723aae1b45f733f702abb4333137143909f"},{"url":"https://git.kernel.org/stable/c/f14858bc77c567e089965962877ee726ffad0556"},{"url":"https://git.kernel.org/stable/c/a4f1a01b2e81378fce9ca528d4d8a049e4b58fcd"},{"url":"https://git.kernel.org/stable/c/612c977f5d481f551d03d83d0aef588845c1300c"},{"url":"https://git.kernel.org/stable/c/52f1c45dde9136f964d63a77d19826c8a74e2c7f"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The recursive deadlock is reached from p9_read_work()/p9_poll_mux() on the TCP (and unix) fd transport when processing peer-driven I/O errors or malformed replies; a remote malicious 9p server can close the connection or send bad headers/tags over the established TCP session to enter p9_conn_cancel().\nAC:L - After a request is fully written the writer has already put its ref, leaving the waiting client with refcount 1; the remote peer can then deterministically force cancel (ECONNRESET, bad header, unexpected tag), so p9_client_cb()'s final p9_req_put() re-takes client->lock with no race outside attacker control.\nPR:N - The attacker is the remote 9p server and needs no credentials or capabilities on the client; reply/error handling on the transport runs without authentication or privilege checks, matching other trans_fd peer-driven 9p client bugs.\nUI:N - Exploitation rides an already-configured or automounted 9p TCP session and server-driven errors/replies; the mount is a deployment precondition, not a required victim action beyond ordinary use of that mount.\nS:U - Impact is a host-kernel deadlock inside the 9p client on the same OS security authority; there is no VM escape, IOMMU bypass, or other cross-boundary effect.\nC:N - This is a pure recursive spinlock deadlock (p9_conn_cancel → p9_client_cb → p9_req_put → p9_tag_remove on the same client->lock); it does not free early, leak, or otherwise disclose kernel memory.\nI:N - There is no memory corruption, UAF, or write primitive—only nested acquisition of the same non-recursive spinlock—so control-flow hijack or arbitrary modification is not available.\nA:H - Re-taking client->lock while already holding it deadlocks the p9_read_work kworker with preemption disabled, hangs all further 9p operations on that client, and can soft-lockup the CPU; syzbot reported the recursive lock in p9_req_put from this path."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:56:16.608Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.127","versionEndExcluding":"4.9.334"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.70","versionEndExcluding":"4.14.300"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"4.19.267"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.4.225"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.10.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.15.80"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18.8"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}