On 7/14/2026 11:26 AM, Roberto Sassu wrote:
On Tue, 2026-07-14 at 17:17 +0800, Gaosheng Cui wrote:
When hashing large files, the while loop in ima_calc_file_hash_tfm
processes PAGE_SIZE chunks without any scheduling point, which can
cause soft lockup warnings:
watchdog: BUG: soft lockup - CPU#0 stuck for 50s!
Call Trace:
_sha256_update+0x12d/0x1a0
ima_calc_file_hash_tfm+0xfb/0x150
ima_calc_file_hash+0x6e/0x160
ima_collect_measurement+0x202/0x340
process_measurement+0x3a9/0xb30
ima_file_check+0x56/0xa0
do_open+0x11b/0x250
path_openat+0x10b/0x1d0
do_filp_open+0xa9/0x150
do_sys_openat2+0x223/0x2a0
__x64_sys_openat+0x54/0xa0
do_syscall_64+0x59/0x110
entry_SYSCALL_64_after_hwframe+0x78/0xe2
Call cond_resched() every 4MB to yield the CPU when needed, rather
than at every loop iteration, to reduce overhead.
Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider")
Signed-off-by: Gaosheng Cui <[email protected]>
Reviewed-by: Roberto Sassu <[email protected]>
Actually, as Sashiko pointed out, alignment does not work well, since
__kernel_read() can return fewer than PAGE_SIZE bytes, causing the
offset to be always misaligned. Instead, we can keep a variable with the
number of bytes read since last cond_resched(), which we reset when we
hit 4 MB.
Sashiko also noted that the same mechanism could apply for
calc_buffer_shash_tfm(), but we can add it later if we have a warning
(note that in this case we already have the buffer, we are not doing
I/O).
Thanks
Roberto
Thanks
Roberto
---
v2: call cond_resched() every 4MB to yield the CPU when needed
security/integrity/ima/ima_crypto.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/security/integrity/ima/ima_crypto.c
b/security/integrity/ima/ima_crypto.c
index 0d72b48249ee..aab2349c0c33 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -233,6 +233,9 @@ static int ima_calc_file_hash_tfm(struct file *file,
rc = crypto_shash_update(shash, rbuf, rbuf_len);
if (rc)
break;
+
+ if (IS_ALIGNED(offset, SZ_4M))
+ cond_resched();
}
kfree(rbuf);
out:
