CVE - CVE-2025-21658

CVE-ID
CVE-2025-21658	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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: <TASK> 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 </TASK> [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 do scrub. So for kernels older than 6.6, the fix will need manual backport.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638a URL:https://git.kernel.org/stable/c/24b85a8b0310e0144da9ab30be42e87e6476638a MISC:https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329 URL:https://git.kernel.org/stable/c/6aecd91a5c5b68939cf4169e32bc49f3cd2dd329 MISC:https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784 URL:https://git.kernel.org/stable/c/aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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