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Btrfs: do not overwrite error return value in the get device stats ioctl

PATCH In review [email protected] 2 participants 2 messages Dec 14, 2018 – Dec 17, 2018 Btrfs file system

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PATCH 1/1 Btrfs: do not overwrite error return value in the get device stats ioctl

From: Filipe Manana <[email protected]>

If the call to btrfs_get_dev_stats() failed we would overwrite the error returned to user space with -EFAULT if the call to copy_to_user() failed as well. Fix that by calling copy_to_user() only if btrfs_get_dev_stats() returned success.

Signed-off-by Filipe Manana <[email protected]>
---
 fs/btrfs/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
fs/btrfs/ioctl.c +1 -1
index 76848214a39f..0b101df822e9 100644
@@ -4355,7 +4355,7 @@ static long btrfs_ioctl_get_dev_stats(struct btrfs_fs_info *fs_info,
 
 	ret = btrfs_get_dev_stats(fs_info, sa);
 
-	if (copy_to_user(arg, sa, sizeof(*sa)))
+	if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
 		ret = -EFAULT;
 
 	kfree(sa);
Signature · 1 line
2.11.0
Reviewed-by on v1 1/1
#1 lore raw

Looks good,

Reviewed-by Johannes Thumshirn <[email protected]>

But I agree with Nick's review on the scrub progress ioctl patch, splitting the error handling into two parts is easier to read.

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Johannes Thumshirn                            SUSE Labs Filesystems
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