Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: handle csum tree...
In the Linux kernel, the following vulnerability has been resolved:
btrfs: handle csum tree error with rescue=ibadroots correctly
[BUG]
There is syzbot based reproducer that can crash the kernel, with the
following call trace: (With some debug output added)
DEBUG: rescue=ibadroots parsed
BTRFS: device fsid 14d642db-7b15-43e4-81e6-4b8fac6a25f8 devid 1 transid 8 /dev/loop0 (7:0) scanned by repro (1010)
BTRFS info (device loop0): first mount of filesystem 14d642db-7b15-43e4-81e6-4b8fac6a25f8
BTRFS info (device loop0): using blake2b (blake2b-256-generic) checksum algorithm
BTRFS info (device loop0): using free-space-tree
BTRFS warning (device loop0): checksum verify failed on logical 5312512 mirror 1 wanted 0xb043382657aede36608fd3386d6b001692ff406164733d94e2d9a180412c6003 found 0x810ceb2bacb7f0f9eb2bf3b2b15c02af867cb35ad450898169f3b1f0bd818651 level 0
DEBUG: read tree root path failed for tree csum, ret=-5
BTRFS warning (device loop0): checksum verify failed on logical 5328896 mirror 1 wanted 0x51be4e8b303da58e6340226815b70e3a93592dac3f30dd510c7517454de8567a found 0x51be4e8b303da58e634022a315b70e3a93592dac3f30dd510c7517454de8567a level 0
BTRFS warning (device loop0): checksum verify failed on logical 5292032 mirror 1 wanted 0x1924ccd683be9efc2fa98582ef58760e3848e9043db8649ee382681e220cdee4 found 0x0cb6184f6e8799d9f8cb335dccd1d1832da1071d12290dab3b85b587ecacca6e level 0
process 'repro' launched './file2' with NULL argv: empty string added
DEBUG: no csum root, idatacsums=0 ibadroots=134217728
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000041: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000208-0x000000000000020f]
CPU: 5 UID: 0 PID: 1010 Comm: repro Tainted: G OE 6.15.0-custom+ #249 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022
RIP: 0010:btrfs_lookup_csum+0x93/0x3d0 [btrfs]
Call Trace:
btrfs_lookup_bio_sums+0x47a/0xdf0 [btrfs]
btrfs_submit_bbio+0x43e/0x1a80 [btrfs]
submit_one_bio+0xde/0x160 [btrfs]
btrfs_readahead+0x498/0x6a0 [btrfs]
read_pages+0x1c3/0xb20
page_cache_ra_order+0x4b5/0xc20
filemap_get_pages+0x2d3/0x19e0
filemap_read+0x314/0xde0
__kernel_read+0x35b/0x900
bprm_execve+0x62e/0x1140
do_execveat_common.isra.0+0x3fc/0x520
__x64_sys_execveat+0xdc/0x130
do_syscall_64+0x54/0x1d0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
---[ end trace 0000000000000000 ]---
[CAUSE]
Firstly the fs has a corrupted csum tree root, thus to mount the fs we
have to go "ro,rescue=ibadroots" mount option.
Normally with that mount option, a bad csum tree root should set
BTRFS_FS_STATE_NO_DATA_CSUMS flag, so that any future data read will
ignore csum search.
But in this particular case, we have the following call trace that
caused NULL csum root, but not setting BTRFS_FS_STATE_NO_DATA_CSUMS:
load_global_roots_objectid():
ret = btrfs_search_slot();
/* Succeeded */
btrfs_item_key_to_cpu()
found = true;
/* We found the root item for csum tree. */
root = read_tree_root_path();
if (IS_ERR(root)) {
if (!btrfs_test_opt(fs_info, IGNOREBADROOTS))
/*
* Since we have rescue=ibadroots mount option,
* @ret is still 0.
*/
break;
if (!found || ret) {
/* @found is true, @ret is 0, error handling for csum
* tree is skipped.
*/
}
This means we completely skipped to set BTRFS_FS_STATE_NO_DATA_CSUMS if
the csum tree is corrupted, which results unexpected later csum lookup.
[FIX]
If read_tree_root_path() failed, always populate @ret to the error
number.
As at the end of the function, we need @ret to determine if we need to
do the extra error handling for csum tree.
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2025-38260 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-38260? CVE-2025-38260 is a medium-severity null pointer dereference vulnerability. No fixed version is listed yet. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2025-38260? CVE-2025-38260 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-38260? No fixed version is listed for CVE-2025-38260 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-38260 exploitable, and should I be worried? Whether CVE-2025-38260 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-38260 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.