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udf: Check component length before reading it

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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>
This commit is contained in:
Jan Kara 2014-12-19 14:27:55 +01:00
parent 0e5cc9a40a
commit e237ec37ec
1 changed files with 7 additions and 2 deletions
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9
fs/udf/symlink.c
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@ -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';