| { |
| "containers": { |
| "cna": { |
| "providerMetadata": { |
| "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038" |
| }, |
| "descriptions": [ |
| { |
| "lang": "en", |
| "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlocking/qrwlock: Fix ordering in queued_write_lock_slowpath()\n\nWhile this code is executed with the wait_lock held, a reader can\nacquire the lock without holding wait_lock. The writer side loops\nchecking the value with the atomic_cond_read_acquire(), but only truly\nacquires the lock when the compare-and-exchange is completed\nsuccessfully which isn’t ordered. This exposes the window between the\nacquire and the cmpxchg to an A-B-A problem which allows reads\nfollowing the lock acquisition to observe values speculatively before\nthe write lock is truly acquired.\n\nWe've seen a problem in epoll where the reader does a xchg while\nholding the read lock, but the writer can see a value change out from\nunder it.\n\n Writer | Reader\n --------------------------------------------------------------------------------\n ep_scan_ready_list() |\n |- write_lock_irq() |\n |- queued_write_lock_slowpath() |\n\t|- atomic_cond_read_acquire() |\n\t\t\t\t | read_lock_irqsave(&ep->lock, flags);\n --> (observes value before unlock) | chain_epi_lockless()\n | | epi->next = xchg(&ep->ovflist, epi);\n | | read_unlock_irqrestore(&ep->lock, flags);\n | |\n | atomic_cmpxchg_relaxed() |\n |-- READ_ONCE(ep->ovflist); |\n\nA core can order the read of the ovflist ahead of the\natomic_cmpxchg_relaxed(). Switching the cmpxchg to use acquire\nsemantics addresses this issue at which point the atomic_cond_read can\nbe switched to use relaxed semantics.\n\n[peterz: use try_cmpxchg()]" |
| } |
| ], |
| "affected": [ |
| { |
| "product": "Linux", |
| "vendor": "Linux", |
| "defaultStatus": "unaffected", |
| "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", |
| "programFiles": [ |
| "kernel/locking/qrwlock.c" |
| ], |
| "versions": [ |
| { |
| "version": "b519b56e378ee82caf9b079b04f5db87dedc3251", |
| "lessThan": "5902f9453a313be8fe78cbd7e7ca9dba9319fc6e", |
| "status": "affected", |
| "versionType": "git" |
| }, |
| { |
| "version": "b519b56e378ee82caf9b079b04f5db87dedc3251", |
| "lessThan": "82808cc026811fbc3ecf0c0b267a12a339eead56", |
| "status": "affected", |
| "versionType": "git" |
| }, |
| { |
| "version": "b519b56e378ee82caf9b079b04f5db87dedc3251", |
| "lessThan": "82fa9ced35d88581cffa4a1c856fc41fca96d80a", |
| "status": "affected", |
| "versionType": "git" |
| }, |
| { |
| "version": "b519b56e378ee82caf9b079b04f5db87dedc3251", |
| "lessThan": "d558fcdb17139728347bccc60a16af3e639649d2", |
| "status": "affected", |
| "versionType": "git" |
| }, |
| { |
| "version": "b519b56e378ee82caf9b079b04f5db87dedc3251", |
| "lessThan": "84a24bf8c52e66b7ac89ada5e3cfbe72d65c1896", |
| "status": "affected", |
| "versionType": "git" |
| } |
| ] |
| }, |
| { |
| "product": "Linux", |
| "vendor": "Linux", |
| "defaultStatus": "affected", |
| "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", |
| "programFiles": [ |
| "kernel/locking/qrwlock.c" |
| ], |
| "versions": [ |
| { |
| "version": "4.15", |
| "status": "affected" |
| }, |
| { |
| "version": "0", |
| "lessThan": "4.15", |
| "status": "unaffected", |
| "versionType": "semver" |
| }, |
| { |
| "version": "4.19.189", |
| "lessThanOrEqual": "4.19.*", |
| "status": "unaffected", |
| "versionType": "semver" |
| }, |
| { |
| "version": "5.4.115", |
| "lessThanOrEqual": "5.4.*", |
| "status": "unaffected", |
| "versionType": "semver" |
| }, |
| { |
| "version": "5.10.33", |
| "lessThanOrEqual": "5.10.*", |
| "status": "unaffected", |
| "versionType": "semver" |
| }, |
| { |
| "version": "5.11.17", |
| "lessThanOrEqual": "5.11.*", |
| "status": "unaffected", |
| "versionType": "semver" |
| }, |
| { |
| "version": "5.12", |
| "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": "4.15", |
| "versionEndExcluding": "4.19.189" |
| }, |
| { |
| "vulnerable": true, |
| "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", |
| "versionStartIncluding": "4.15", |
| "versionEndExcluding": "5.4.115" |
| }, |
| { |
| "vulnerable": true, |
| "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", |
| "versionStartIncluding": "4.15", |
| "versionEndExcluding": "5.10.33" |
| }, |
| { |
| "vulnerable": true, |
| "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", |
| "versionStartIncluding": "4.15", |
| "versionEndExcluding": "5.11.17" |
| }, |
| { |
| "vulnerable": true, |
| "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", |
| "versionStartIncluding": "4.15", |
| "versionEndExcluding": "5.12" |
| } |
| ] |
| } |
| ] |
| } |
| ], |
| "references": [ |
| { |
| "url": "https://git.kernel.org/stable/c/5902f9453a313be8fe78cbd7e7ca9dba9319fc6e" |
| }, |
| { |
| "url": "https://git.kernel.org/stable/c/82808cc026811fbc3ecf0c0b267a12a339eead56" |
| }, |
| { |
| "url": "https://git.kernel.org/stable/c/82fa9ced35d88581cffa4a1c856fc41fca96d80a" |
| }, |
| { |
| "url": "https://git.kernel.org/stable/c/d558fcdb17139728347bccc60a16af3e639649d2" |
| }, |
| { |
| "url": "https://git.kernel.org/stable/c/84a24bf8c52e66b7ac89ada5e3cfbe72d65c1896" |
| } |
| ], |
| "title": "locking/qrwlock: Fix ordering in queued_write_lock_slowpath()", |
| "x_generator": { |
| "engine": "bippy-1.2.0" |
| } |
| } |
| }, |
| "cveMetadata": { |
| "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038", |
| "cveID": "CVE-2021-46921", |
| "requesterUserId": "gregkh@kernel.org", |
| "serial": "1", |
| "state": "PUBLISHED" |
| }, |
| "dataType": "CVE_RECORD", |
| "dataVersion": "5.0" |
| } |
