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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-18 15:43:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-07-19 21:49:01 -0700 |
| commit | 59430262401bec02d415179c43dbe5b8819c09ce (patch) | |
| tree | 18caba988f1fb650bb804727de06adc73953b2c6 /fs | |
| parent | fec11dd9a0109fe52fd631e5c510778d6cbff6cc (diff) | |
| download | linux-3.10-59430262401bec02d415179c43dbe5b8819c09ce.tar.gz linux-3.10-59430262401bec02d415179c43dbe5b8819c09ce.tar.bz2 linux-3.10-59430262401bec02d415179c43dbe5b8819c09ce.zip | |
vfs: fix race in rcu lookup of pruned dentry
Don't update *inode in __follow_mount_rcu() until we'd verified that
there is mountpoint there. Kudos to Hugh Dickins for catching that
one in the first place and eventually figuring out the solution (and
catching a braino in the earlier version of patch).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namei.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/namei.c b/fs/namei.c index 5c867dd1c0b..14ab8d3f2f0 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -942,7 +942,6 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, * Don't forget we might have a non-mountpoint managed dentry * that wants to block transit. */ - *inode = path->dentry->d_inode; if (unlikely(managed_dentry_might_block(path->dentry))) return false; @@ -955,6 +954,12 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, path->mnt = mounted; path->dentry = mounted->mnt_root; nd->seq = read_seqcount_begin(&path->dentry->d_seq); + /* + * Update the inode too. We don't need to re-check the + * dentry sequence number here after this d_inode read, + * because a mount-point is always pinned. + */ + *inode = path->dentry->d_inode; } return true; } |