发布于3月6日3月6日 Members Ubuntu: (Multiple Advisories) (CVE-2024-35877): Linux kernel vulnerabilities Severity 4 CVSS (AV:L/AC:M/Au:N/C:P/I:P/A:P) Published 05/19/2024 Created 07/12/2024 Added 07/12/2024 Modified 12/11/2024 Description In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: fix VM_PAT handling in COW mappings PAT handling won't do the right thing in COW mappings: the first PTE (or, in fact, all PTEs) can be replaced during write faults to point at anon folios.Reliably recovering the correct PFN and cachemode using follow_phys() from PTEs will not work in COW mappings. Using follow_phys(), we might just get the address+protection of the anon folio (which is very wrong), or fail on swap/nonswap entries, failing follow_phys() and triggering a WARN_ON_ONCE() in untrack_pfn() and track_pfn_copy(), not properly calling free_pfn_range(). In free_pfn_range(), we either wouldn't call memtype_free() or would call it with the wrong range, possibly leaking memory. To fix that, let's update follow_phys() to refuse returning anon folios, and fallback to using the stored PFN inside vma->vm_pgoff for COW mappings if we run into that. We will now properly handle untrack_pfn() with COW mappings, where we don't need the cachemode.We'll have to fail fork()->track_pfn_copy() if the first page was replaced by an anon folio, though: we'd have to store the cachemode in the VMA to make this work, likely growing the VMA size. For now, lets keep it simple and let track_pfn_copy() just fail in that case: it would have failed in the past with swap/nonswap entries already, and it would have done the wrong thing with anon folios. Simple reproducer to trigger the WARN_ON_ONCE() in untrack_pfn(): <--- C reproducer ---> #include <stdio.h> #include <sys/mman.h> #include <unistd.h> #include <liburing.h> int main(void) { struct io_uring_params p = {}; int ring_fd; size_t size; char *map; ring_fd = io_uring_setup(1, &p); if (ring_fd < 0) { perror("io_uring_setup"); return 1; } size = p.sq_off.array + p.sq_entries * sizeof(unsigned); /* Map the submission queue ring MAP_PRIVATE */ map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, ring_fd, IORING_OFF_SQ_RING); if (map == MAP_FAILED) { perror("mmap"); return 1; } /* We have at least one page. Let's COW it. */ *map = 0; pause(); return 0; } <--- C reproducer ---> On a system with 16 GiB RAM and swap configured: # ./iouring & # memhog 16G # killall iouring [301.552930] ------------[ cut here ]------------ [301.553285] WARNING: CPU: 7 PID: 1402 at arch/x86/mm/pat/memtype.c:1060 untrack_pfn+0xf4/0x100 [301.553989] Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_g [301.558232] CPU: 7 PID: 1402 Comm: iouring Not tainted 6.7.5-100.fc38.x86_64 #1 [301.558772] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebu4 [301.559569] RIP: 0010:untrack_pfn+0xf4/0x100 [301.559893] Code: 75 c4 eb cf 48 8b 43 10 8b a8 e8 00 00 00 3b 6b 28 74 b8 48 8b 7b 30 e8 ea 1a f7 000 [301.561189] RSP: 0018:ffffba2c0377fab8 EFLAGS: 00010282 [301.561590] RAX: 00000000ffffffea RBX: ffff9208c8ce9cc0 RCX: 000000010455e047 [301.562105] RDX: 07fffffff0eb1e0a RSI: 0000000000000000 RDI: ffff9208c391d200 [301.562628] RBP: 0000000000000000 R08: ffffba2c0377fab8 R09: 0000000000000000 [301.563145] R10: ffff9208d2292d50 R11: 0000000000000002 R12: 00007fea890e0000 [301.563669] R13: 0000000000000000 R14: ffffba2c0377fc08 R15: 0000000000000000 [301.564186] FS:0000000000000000(0000) GS:ffff920c2fbc0000(0000) knlGS:0000000000000000 [301.564773] CS:0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [301.565197] CR2: 00007fea88ee8a20 CR3: 00000001033a8000 CR4: 0000000000750ef0 [301.565725] PKRU: 55555554 [301.565944] Call Trace: [301.566148]<TASK> [301.566325]? untrack_pfn+0xf4/0x100 [301.566618]? __warn+0x81/0x130 [301.566876]? untrack_pfn+0xf4/0x100 [3 ---truncated--- Solution(s) ubuntu-upgrade-linux-image-4-15-0-1137-oracle ubuntu-upgrade-linux-image-4-15-0-1158-kvm ubuntu-upgrade-linux-image-4-15-0-1168-gcp ubuntu-upgrade-linux-image-4-15-0-1175-aws ubuntu-upgrade-linux-image-4-15-0-1183-azure ubuntu-upgrade-linux-image-4-15-0-231-generic ubuntu-upgrade-linux-image-4-15-0-231-lowlatency ubuntu-upgrade-linux-image-4-4-0-1138-aws 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ubuntu-upgrade-linux-image-oracle-lts-18-04 ubuntu-upgrade-linux-image-oracle-lts-20-04 ubuntu-upgrade-linux-image-oracle-lts-22-04 ubuntu-upgrade-linux-image-raspi ubuntu-upgrade-linux-image-raspi-hwe-18-04 ubuntu-upgrade-linux-image-raspi-nolpae ubuntu-upgrade-linux-image-raspi2 ubuntu-upgrade-linux-image-snapdragon-hwe-18-04 ubuntu-upgrade-linux-image-virtual ubuntu-upgrade-linux-image-virtual-hwe-16-04 ubuntu-upgrade-linux-image-virtual-hwe-18-04 ubuntu-upgrade-linux-image-virtual-hwe-20-04 ubuntu-upgrade-linux-image-virtual-hwe-24-04 ubuntu-upgrade-linux-image-virtual-lts-xenial ubuntu-upgrade-linux-image-xilinx-zynqmp References https://attackerkb.com/topics/cve-2024-35877 CVE - 2024-35877 USN-6893-1 USN-6893-2 USN-6893-3 USN-6896-1 USN-6896-2 USN-6896-3 USN-6896-4 USN-6896-5 USN-6898-1 USN-6898-2 USN-6898-3 USN-6898-4 USN-6917-1 USN-6918-1 USN-6919-1 USN-6927-1 USN-7019-1 USN-7121-1 USN-7121-2 USN-7121-3 USN-7148-1 View more
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