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udf: Avoid overflow when session starts at large offset

Message ID 20171016095733.15567-1-jack@suse.cz (mailing list archive)
State New, archived
Headers show

Commit Message

Jan Kara Oct. 16, 2017, 9:57 a.m. UTC
When session starts beyond offset 2^31 the arithmetics in
udf_check_vsd() would overflow. Make sure the computation is done in
large enough type.

Reported-by: Cezary Sliwa <sliwa@ifpan.edu.pl>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/udf/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

I will queue this patch into my tree.
diff mbox

Patch

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 99cb81d0077f..08bf097507f6 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -703,7 +703,7 @@  static loff_t udf_check_vsd(struct super_block *sb)
 	else
 		sectorsize = sb->s_blocksize;
 
-	sector += (sbi->s_session << sb->s_blocksize_bits);
+	sector += (((loff_t)sbi->s_session) << sb->s_blocksize_bits);
 
 	udf_debug("Starting at sector %u (%ld byte sectors)\n",
 		  (unsigned int)(sector >> sb->s_blocksize_bits),