From: Jan Kara Date: Mon, 15 Dec 2014 13:22:46 +0000 (+0100) Subject: isofs: Fix infinite looping over CE entries X-Git-Tag: v3.2.67~93 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=212c4d33ca83e2144064fe9c2911607fbed5386f isofs: Fix infinite looping over CE entries commit f54e18f1b831c92f6512d2eedb224cd63d607d3d upstream. Rock Ridge extensions define so called Continuation Entries (CE) which define where is further space with Rock Ridge data. Corrupted isofs image can contain arbitrarily long chain of these, including a one containing loop and thus causing kernel to end in an infinite loop when traversing these entries. Limit the traversal to 32 entries which should be more than enough space to store all the Rock Ridge data. Reported-by: P J P Signed-off-by: Jan Kara Signed-off-by: Ben Hutchings --- diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c index ee62cc0c2499..26859dea2c46 100644 --- a/fs/isofs/rock.c +++ b/fs/isofs/rock.c @@ -30,6 +30,7 @@ struct rock_state { int cont_size; int cont_extent; int cont_offset; + int cont_loops; struct inode *inode; }; @@ -73,6 +74,9 @@ static void init_rock_state(struct rock_state *rs, struct inode *inode) rs->inode = inode; } +/* Maximum number of Rock Ridge continuation entries */ +#define RR_MAX_CE_ENTRIES 32 + /* * Returns 0 if the caller should continue scanning, 1 if the scan must end * and -ve on error. @@ -105,6 +109,8 @@ static int rock_continue(struct rock_state *rs) goto out; } ret = -EIO; + if (++rs->cont_loops >= RR_MAX_CE_ENTRIES) + goto out; bh = sb_bread(rs->inode->i_sb, rs->cont_extent); if (bh) { memcpy(rs->buffer, bh->b_data + rs->cont_offset,