Description

In the Linux kernel, the following vulnerability has been resolved:

md/md-bitmap: Synchronize bitmap_get_stats() with bitmap lifetime

After commit ec6bb299c7c3 ("md/md-bitmap: add 'sync_size' into struct
md_bitmap_stats"), following panic is reported:

Oops: general protection fault, probably for non-canonical address
RIP: 0010:bitmap_get_stats+0x2b/0xa0
Call Trace:

md_seq_show+0x2d2/0x5b0
seq_read_iter+0x2b9/0x470
seq_read+0x12f/0x180
proc_reg_read+0x57/0xb0
vfs_read+0xf6/0x380
ksys_read+0x6c/0xf0
do_syscall_64+0x82/0x170
entry_SYSCALL_64_after_hwframe+0x76/0x7e

Root cause is that bitmap_get_stats() can be called at anytime if mddev
is still there, even if bitmap is destroyed, or not fully initialized.
Deferenceing bitmap in this case can crash the kernel. Meanwhile, the
above commit start to deferencing bitmap->storage, make the problem
easier to trigger.

Fix the problem by protecting bitmap_get_stats() with bitmap_info.mutex.

Classification

CVE ID: CVE-2025-21712

Affected Products

Vendor: Linux, Linux

Product: Linux, Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.03% (probability of being exploited)

EPSS Percentile: 4.27% (scored less or equal to compared to others)

EPSS Date: 2025-03-27 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-21712
https://git.kernel.org/stable/c/237e19519c8ff6949f0ef57c4a0243f5b2b0fa18
https://git.kernel.org/stable/c/4e9316eee3885bfb311b4759513f2ccf37891c09
https://git.kernel.org/stable/c/8d28d0ddb986f56920ac97ae704cc3340a699a30

Timeline