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authorLinus Torvalds <torvalds@linux-foundation.org>2011-12-26 10:25:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-26 10:25:26 -0800
commit6d4b9e38d3980826abccfbd90e95bf4bd41b8dd2 (patch)
tree7473e333fc5aae6dd1d4b7f86205a330818518ce
parent4962516b2309d76964f9df0d33e74f43b624a42d (diff)
downloadlinux-linaro-6d4b9e38d3980826abccfbd90e95bf4bd41b8dd2.tar.gz
vfs: fix handling of lock allocation failure in lease-break case
Bruce Fields notes that commit 778fc546f749 ("locks: fix tracking of inprogress lease breaks") introduced a possible error pointer dereference on failure to allocate memory. locks_conflict() will dereference the passed-in new lease lock structure that may be an error pointer. This means an open (without O_NONBLOCK set) on a file with a lease applied (generally only done when Samba or nfsd (with v4) is running) could crash if a kmalloc() fails. So instead of playing games with IS_ERROR() all over the place, just check the allocation failure early. That makes the code more straightforward, and avoids this possible bad pointer dereference. Based-on-patch-by: J. Bruce Fields <bfields@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/locks.c11
1 files changed, 3 insertions, 8 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 3b0d05dcd7c..637694bf3a0 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1205,6 +1205,8 @@ int __break_lease(struct inode *inode, unsigned int mode)
int want_write = (mode & O_ACCMODE) != O_RDONLY;
new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
+ if (IS_ERR(new_fl))
+ return PTR_ERR(new_fl);
lock_flocks();
@@ -1221,12 +1223,6 @@ int __break_lease(struct inode *inode, unsigned int mode)
if (fl->fl_owner == current->files)
i_have_this_lease = 1;
- if (IS_ERR(new_fl) && !i_have_this_lease
- && ((mode & O_NONBLOCK) == 0)) {
- error = PTR_ERR(new_fl);
- goto out;
- }
-
break_time = 0;
if (lease_break_time > 0) {
break_time = jiffies + lease_break_time * HZ;
@@ -1284,8 +1280,7 @@ restart:
out:
unlock_flocks();
- if (!IS_ERR(new_fl))
- locks_free_lock(new_fl);
+ locks_free_lock(new_fl);
return error;
}