In the Linux kernel, the following vulnerability has been resolved:
btrfs: avoid NULL pointer dereference if no valid csum tree
[BUG]
When trying read-only scrub on a btrfs with rescue=idatacsums mount
option, it will crash with the following call trace:
BUG: kernel NULL pointer dereference, address: 0000000000000208
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
CPU: 1 UID: 0 PID: 835 Comm: btrfs Tainted: G O 6.15.0-rc3-custom+ #236 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022
RIP: 0010:btrfs_lookup_csums_bitmap+0x49/0x480 [btrfs]
Call Trace:
<TASK>
scrub_find_fill_first_stripe+0x35b/0x3d0 [btrfs]
scrub_simple_mirror+0x175/0x290 [btrfs]
scrub_stripe+0x5f7/0x6f0 [btrfs]
scrub_chunk+0x9a/0x150 [btrfs]
scrub_enumerate_chunks+0x333/0x660 [btrfs]
btrfs_scrub_dev+0x23e/0x600 [btrfs]
btrfs_ioctl+0x1dcf/0x2f80 [btrfs]
__x64_sys_ioctl+0x97/0xc0
do_syscall_64+0x4f/0x120
entry_SYSCALL_64_after_hwframe+0x76/0x7e
[CAUSE]
Mount option "rescue=idatacsums" will completely skip loading the csum
tree, so that any data read will not find any data csum thus we will
ignore data checksum verification.
Normally call sites utilizing csum tree will check the fs state flag
NO_DATA_CSUMS bit, but unfortunately scrub does not check that bit at all.
This results in scrub to call btrfs_search_slot() on a NULL pointer
and triggered above crash.
[FIX]
Check both extent and csum tree root before doing any tree search.
Metrics
Affected Vendors & Products
References
History
Fri, 20 Jun 2025 23:15:00 +0000
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threat_severity
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cvssV3_1
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Wed, 18 Jun 2025 09:45:00 +0000
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Description | In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid csum tree [BUG] When trying read-only scrub on a btrfs with rescue=idatacsums mount option, it will crash with the following call trace: BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page CPU: 1 UID: 0 PID: 835 Comm: btrfs Tainted: G O 6.15.0-rc3-custom+ #236 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:btrfs_lookup_csums_bitmap+0x49/0x480 [btrfs] Call Trace: <TASK> scrub_find_fill_first_stripe+0x35b/0x3d0 [btrfs] scrub_simple_mirror+0x175/0x290 [btrfs] scrub_stripe+0x5f7/0x6f0 [btrfs] scrub_chunk+0x9a/0x150 [btrfs] scrub_enumerate_chunks+0x333/0x660 [btrfs] btrfs_scrub_dev+0x23e/0x600 [btrfs] btrfs_ioctl+0x1dcf/0x2f80 [btrfs] __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e [CAUSE] Mount option "rescue=idatacsums" will completely skip loading the csum tree, so that any data read will not find any data csum thus we will ignore data checksum verification. Normally call sites utilizing csum tree will check the fs state flag NO_DATA_CSUMS bit, but unfortunately scrub does not check that bit at all. This results in scrub to call btrfs_search_slot() on a NULL pointer and triggered above crash. [FIX] Check both extent and csum tree root before doing any tree search. | |
Title | btrfs: avoid NULL pointer dereference if no valid csum tree | |
References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-06-18T09:33:38.943Z
Reserved: 2025-04-16T04:51:23.979Z
Link: CVE-2025-38059

No data.

Status : Awaiting Analysis
Published: 2025-06-18T10:15:38.703
Modified: 2025-06-18T13:46:52.973
Link: CVE-2025-38059
