🛡️ CVE-2025-68740 — kernel

ima: Handle error code returned by ima_filter_rule_match()

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

ima: Handle error code returned by ima_filter_rule_match()

In ima_match_rules(), if ima_filter_rule_match() returns -ENOENT due to

the rule being NULL, the function incorrectly skips the 'if (!rc)' check

and sets 'result = true'. The LSM rule is considered a match, causing

extra files to be measured by IMA.

This issue can be reproduced in the following scenario:

After unloading the SELinux policy module via 'semodule -d', if an IMA

measurement is triggered before ima_lsm_rules is updated,

in ima_match_rules(), the first call to ima_filter_rule_match() returns

-ESTALE. This causes the code to enter the 'if (rc == -ESTALE &&

!rule_reinitialized)' block, perform ima_lsm_copy_rule() and retry. In

ima_lsm_copy_rule(), since the SELinux module has been removed, the rule

becomes NULL, and the second call to ima_filter_rule_match() returns

-ENOENT. This bypasses the 'if (!rc)' check and results in a false match.

Call trace:

selinux_audit_rule_match+0x310/0x3b8

security_audit_rule_match+0x60/0xa0

ima_match_rules+0x2e4/0x4a0

ima_match_policy+0x9c/0x1e8

ima_get_action+0x48/0x60

process_measurement+0xf8/0xa98

ima_bprm_check+0x98/0xd8

security_bprm_check+0x5c/0x78

search_binary_handler+0x6c/0x318

exec_binprm+0x58/0x1b8

bprm_execve+0xb8/0x130

do_execveat_common.isra.0+0x1a8/0x258

__arm64_sys_execve+0x48/0x68

invoke_syscall+0x50/0x128

el0_svc_common.constprop.0+0xc8/0xf0

do_el0_svc+0x24/0x38

el0_svc+0x44/0x200

el0t_64_sync_handler+0x100/0x130

el0t_64_sync+0x3c8/0x3d0

Fix this by changing 'if (!rc)' to 'if (rc <= 0)' to ensure that error

codes like -ENOENT do not bypass the check and accidentally result in a

successful match.