hfsplus: fix possible deadlock when handling corrupted extents

A corrupted extent for the extent file itself may try to get an impossible
extent, causing a deadlock if I see it correctly.

Check the inode number after the first_blocks checks and fail if it's the
extent file, as according to the spec the extent file should have no
extent for itself.

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index fec8f61227ff..0022eec63cda 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -199,6 +199,9 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock,
                 goto done;
         }
 
+        if (inode->i_ino == HFSPLUS_EXT_CNID)
+                return -EIO;
+
         mutex_lock(&HFSPLUS_I(inode).extents_lock);
         res = hfsplus_ext_read_extent(inode, ablock);
         if (!res) {