{ "containers": { "cna": { "providerMetadata": { "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: core: Fix hang in usb_kill_urb by adding memory barriers\n\nThe syzbot fuzzer has identified a bug in which processes hang waiting\nfor usb_kill_urb() to return. It turns out the issue is not unlinking\nthe URB; that works just fine. Rather, the problem arises when the\nwakeup notification that the URB has completed is not received.\n\nThe reason is memory-access ordering on SMP systems. In outline form,\nusb_kill_urb() and __usb_hcd_giveback_urb() operating concurrently on\ndifferent CPUs perform the following actions:\n\nCPU 0\t\t\t\t\tCPU 1\n----------------------------\t\t---------------------------------\nusb_kill_urb():\t\t\t\t__usb_hcd_giveback_urb():\n ...\t\t\t\t\t ...\n atomic_inc(&urb->reject);\t\t atomic_dec(&urb->use_count);\n ...\t\t\t\t\t ...\n wait_event(usb_kill_urb_queue,\n\tatomic_read(&urb->use_count) == 0);\n\t\t\t\t\t if (atomic_read(&urb->reject))\n\t\t\t\t\t\twake_up(&usb_kill_urb_queue);\n\nConfining your attention to urb->reject and urb->use_count, you can\nsee that the overall pattern of accesses on CPU 0 is:\n\n\twrite urb->reject, then read urb->use_count;\n\nwhereas the overall pattern of accesses on CPU 1 is:\n\n\twrite urb->use_count, then read urb->reject.\n\nThis pattern is referred to in memory-model circles as SB (for \"Store\nBuffering\"), and it is well known that without suitable enforcement of\nthe desired order of accesses -- in the form of memory barriers -- it\nis entirely possible for one or both CPUs to execute their reads ahead\nof their writes. The end result will be that sometimes CPU 0 sees the\nold un-decremented value of urb->use_count while CPU 1 sees the old\nun-incremented value of urb->reject. Consequently CPU 0 ends up on\nthe wait queue and never gets woken up, leading to the observed hang\nin usb_kill_urb().\n\nThe same pattern of accesses occurs in usb_poison_urb() and the\nfailure pathway of usb_hcd_submit_urb().\n\nThe problem is fixed by adding suitable memory barriers. To provide\nproper memory-access ordering in the SB pattern, a full barrier is\nrequired on both CPUs. The atomic_inc() and atomic_dec() accesses\nthemselves don't provide any memory ordering, but since they are\npresent, we can use the optimized smp_mb__after_atomic() memory\nbarrier in the various routines to obtain the desired effect.\n\nThis patch adds the necessary memory barriers." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/usb/core/hcd.c", "drivers/usb/core/urb.c" ], "versions": [ { "version": "1da177e4c3f4", "lessThan": "5f138ef224df", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "b50f5ca60475", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "546ba238535d", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "5904dfd3ddaf", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "9c61fce322ac", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "e3b131e30e61", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "9340226388c6", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "c9a18f7c5b07", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f4", "lessThan": "26fbe9772b8c", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/usb/core/hcd.c", "drivers/usb/core/urb.c" ], "versions": [ { "version": "4.4.302", "lessThanOrEqual": "4.4.*", "status": "unaffected", "versionType": "custom" }, { "version": "4.9.300", "lessThanOrEqual": "4.9.*", "status": "unaffected", "versionType": "custom" }, { "version": "4.14.265", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "custom" }, { "version": "4.19.228", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.4.176", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.10.96", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.15.19", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.16.5", "lessThanOrEqual": "5.16.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.17", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5f138ef224dffd15d5e5c5b095859719e0038427" }, { "url": "https://git.kernel.org/stable/c/b50f5ca60475710bbc9a3af32fbfc17b1e69c2f0" }, { "url": "https://git.kernel.org/stable/c/546ba238535d925254e0b3f12012a5c55801e2f3" }, { "url": "https://git.kernel.org/stable/c/5904dfd3ddaff3bf4a41c3baf0a8e8f31ed4599b" }, { "url": "https://git.kernel.org/stable/c/9c61fce322ac2ef7fecf025285353570d60e41d6" }, { "url": "https://git.kernel.org/stable/c/e3b131e30e612ff0e32de6c1cb4f69f89db29193" }, { "url": "https://git.kernel.org/stable/c/9340226388c66a7e090ebb00e91ed64a753b6c26" }, { "url": "https://git.kernel.org/stable/c/c9a18f7c5b071dce5e6939568829d40994866ab0" }, { "url": "https://git.kernel.org/stable/c/26fbe9772b8c459687930511444ce443011f86bf" } ], "title": "USB: core: Fix hang in usb_kill_urb by adding memory barriers", "x_generator": { "engine": "bippy-7d53e8ef8be4" } } }, "cveMetadata": { "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038", "cveID": "CVE-2022-48760", "requesterUserId": "gregkh@kernel.org", "serial": "1", "state": "PUBLISHED" }, "dataType": "CVE_RECORD", "dataVersion": "5.0" }