cbcvebase.
CVE-2025-21658
published 2025-01-21

CVE-2025-21658: In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.20%
10.1th percentile
In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash with the following call trace: BTRFS info (device loop0): scrub: started on devid 1 BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Call Trace: scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] scrub_simple_mirror+0x175/0x260 [btrfs] scrub_stripe+0x5d4/0x6c0 [btrfs] scrub_chunk+0xbb/0x170 [btrfs] scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e [CAUSE] The reproducer is using a corrupted image where extent tree root is corrupted, thus forcing to use "rescue=all,ro" mount option to mount the image. Then it triggered a scrub, but since scrub relies on extent tree to find where the data/metadata extents are, scrub_find_fill_first_stripe() relies on an non-empty extent root. But unfortunately scrub_find_fill_first_stripe() doesn't really expect an NULL pointer for extent root, it use extent_root to grab fs_info and triggered a NULL pointer dereference. [FIX] Add an extra check for a valid extent root at the beginning of scrub_find_fill_first_stripe(). The new error path is introduced by 42437a6386ff ("btrfs: introduce mount option rescue=ignorebadroots"), but that's pretty old, and later commit b979547513ff ("btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe") changed how we d

Affected

13 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.12.10-1 (forky)linux 6.12.10-1 (forky)
linuxlinux
linuxlinux>= 42437a6386ffeaaf200731e73d723ea491f3fe7d < 24b85a8b0310e0144da9ab30be42e87e6476638a24b85a8b0310e0144da9ab30be42e87e6476638a
linuxlinux>= 42437a6386ffeaaf200731e73d723ea491f3fe7d < aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784
linuxlinux>= 42437a6386ffeaaf200731e73d723ea491f3fe7d < 6aecd91a5c5b68939cf4169e32bc49f3cd2dd3296aecd91a5c5b68939cf4169e32bc49f3cd2dd329
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.12.10-16.12.10-1
linuxlinux_kernel>= 0 < 6.12.10-16.12.10-1
linuxlinux_kernel>= 0 < 6.8.0-60.636.8.0-60.63
linuxlinux_kernel>= 5.11 < 6.6.726.6.72
linuxlinux_kernel>= 6.7 < 6.12.106.12.10
msrccbl2_rust_1.59.0-1_on_cbl_mariner_2.0
msrccm1_rust_1.59.0-1_on_cbl_mariner_1.0

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.8HIGH
vendor_ubuntu7.8HIGH
vendor_msrc6.3MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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