linux-ext4 - [PATCH] ext4: in ext4_seek_{hole,data}, return -ENXIO for negative offsets

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Date:   Wed, 12 Jul 2017 10:32:32 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     "Theodore Ts'o" <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org, Mateusz S <muttdini@...il.com>
Subject: [PATCH] ext4: in ext4_seek_{hole,data}, return -ENXIO for negative
 offsets

NOTE: The pending iomap SEEK_HOLE/DATA conversion patch will make all this
obsolete; this is a fix more appropriate for pre-4.13 ext4.
---
In the ext4 implementations of SEEK_HOLE and SEEK_DATA, make sure we
return -ENXIO for negative offsets instead of banging around inside
the extent code and returning -EFSCORRUPTED.

Reported-by: Mateusz S <muttdini@...il.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 fs/ext4/file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 02ce7e7..923e765 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -576,7 +576,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 	inode_lock(inode);
 
 	isize = i_size_read(inode);
-	if (offset >= isize) {
+	if (offset < 0 || offset >= isize) {
 		inode_unlock(inode);
 		return -ENXIO;
 	}
@@ -639,7 +639,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 	inode_lock(inode);
 
 	isize = i_size_read(inode);
-	if (offset >= isize) {
+	if (offset < 0 || offset >= isize) {
 		inode_unlock(inode);
 		return -ENXIO;
 	}