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authorJan Kara <jack@suse.cz>2014-12-19 14:27:55 +0100
committerJan Kara <jack@suse.cz>2014-12-21 22:42:19 +0100
commite237ec37ec154564f8690c5bd1795339955eeef9 (patch)
tree33e14928a5c2fdee03df67e2e1e4f9991e056fc7
parent0e5cc9a40ada6046e6bc3bdfcd0c0d7e4b706b14 (diff)
udf: Check component length before reading it
Check that length specified in a component of a symlink fits in the input buffer we are reading. Also properly ignore component length for component types that do not use it. Otherwise we read memory after end of buffer for corrupted udf image. Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no> CC: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz>
-rw-r--r--fs/udf/symlink.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index 0f1b3a2654b9..ac10ca939f26 100644
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -42,14 +42,17 @@ static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
tolen--;
while (elen < fromlen) {
pc = (struct pathComponent *)(from + elen);
+ elen += sizeof(struct pathComponent);
switch (pc->componentType) {
case 1:
/*
* Symlink points to some place which should be agreed
* upon between originator and receiver of the media. Ignore.
*/
- if (pc->lengthComponentIdent > 0)
+ if (pc->lengthComponentIdent > 0) {
+ elen += pc->lengthComponentIdent;
break;
+ }
/* Fall through */
case 2:
if (tolen == 0)
@@ -74,6 +77,9 @@ static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
/* that would be . - just ignore */
break;
case 5:
+ elen += pc->lengthComponentIdent;
+ if (elen > fromlen)
+ return -EIO;
comp_len = udf_get_filename(sb, pc->componentIdent,
pc->lengthComponentIdent,
p, tolen);
@@ -85,7 +91,6 @@ static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
tolen--;
break;
}
- elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
}
if (p > to + 1)
p[-1] = '\0';

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