Probably spitting WARNs on user supplied output looks more like a debug
approach. So if this WARN_ONCE is breaking some tests we should just
remove that instead of changing it into pr_warn_ratelimited.
On 7/6/26 14:11, Andrey Zhadchenko wrote:
I don't like that. Customers do not run with panic_on_warn. If this
fails in our test environment, that's actually great (it means something
went very wrong). pr_warn_ratelimited is worse than WARN_ONCE regarding
intentional spamming.
On 7/6/26 12:59, Konstantin Khorenko wrote:
blk_cbt_ioctl() reads abi_version straight from the ioctl argument and
WARN_ONCE()s if it does not match CBT_ABI_VERSION. The value is fully
userspace-controlled, so any process issuing a BLKCBT* ioctl with a
stale/newer struct taints the kernel, dumps a backtrace, and can panic a
host that runs with panic_on_warn. Downgrade to pr_warn_ratelimited();
the -EOPNOTSUPP return is the actual contract.
Fixes: 6e42f62a2c88 ("block/blk-cbt: introduce ABI versioning")
Feature: cbt: changed block tracking (for backup)
https://virtuozzo.atlassian.net/browse/VSTOR-137234
Signed-off-by: Konstantin Khorenko <[email protected]>
---
block/blk-cbt.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-cbt.c b/block/blk-cbt.c
index 90219f58f1ae..91a888770411 100644
--- a/block/blk-cbt.c
+++ b/block/blk-cbt.c
@@ -1093,8 +1093,8 @@ int blk_cbt_ioctl(struct block_device *bdev,
unsigned cmd, char __user *arg)
return -EFAULT;
if (abi_version != CBT_ABI_VERSION) {
- WARN_ONCE(1, "blk-cbt ABI mimatch: kernel has %d, userspace
uses %d",
- CBT_ABI_VERSION, abi_version);
+ pr_warn_ratelimited("blk-cbt: ABI mismatch: kernel has %d,
userspace uses %d\n",
+ CBT_ABI_VERSION, abi_version);
return -EOPNOTSUPP;
}
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