diff options
| author | David Howells <dhowells@redhat.com> | 2020-01-14 19:16:25 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-14 20:40:06 +0300 |
| commit | 40a708bd622b78582ae3d280de29b09b50bd04c0 (patch) | |
| tree | 2a359efe3c25cac13f68e7847925888fc160bc21 | |
| parent | 8379bb84be757d5df2d818509faec5d66adb861d (diff) | |
| download | linux-40a708bd622b78582ae3d280de29b09b50bd04c0.tar.xz | |
afs: Fix use-after-loss-of-ref
afs_lookup() has a tracepoint to indicate the outcome of
d_splice_alias(), passing it the inode to retrieve the fid from.
However, the function gave up its ref on that inode when it called
d_splice_alias(), which may have failed and dropped the inode.
Fix this by caching the fid.
Fixes: 80548b03991f ("afs: Add more tracepoints")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/afs/dir.c | 12 | ||||
| -rw-r--r-- | include/trace/events/afs.h | 12 |
2 files changed, 10 insertions, 14 deletions
diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 497f979018c2..813db1708494 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -908,6 +908,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { struct afs_vnode *dvnode = AFS_FS_I(dir); + struct afs_fid fid = {}; struct inode *inode; struct dentry *d; struct key *key; @@ -957,15 +958,16 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, dentry->d_fsdata = (void *)(unsigned long)dvnode->status.data_version; } + + if (!IS_ERR_OR_NULL(inode)) + fid = AFS_FS_I(inode)->fid; + d = d_splice_alias(inode, dentry); if (!IS_ERR_OR_NULL(d)) { d->d_fsdata = dentry->d_fsdata; - trace_afs_lookup(dvnode, &d->d_name, - inode ? AFS_FS_I(inode) : NULL); + trace_afs_lookup(dvnode, &d->d_name, &fid); } else { - trace_afs_lookup(dvnode, &dentry->d_name, - IS_ERR_OR_NULL(inode) ? NULL - : AFS_FS_I(inode)); + trace_afs_lookup(dvnode, &dentry->d_name, &fid); } return d; } diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h index d5ec4fac82ae..564ba1b5cf57 100644 --- a/include/trace/events/afs.h +++ b/include/trace/events/afs.h @@ -915,9 +915,9 @@ TRACE_EVENT(afs_call_state, TRACE_EVENT(afs_lookup, TP_PROTO(struct afs_vnode *dvnode, const struct qstr *name, - struct afs_vnode *vnode), + struct afs_fid *fid), - TP_ARGS(dvnode, name, vnode), + TP_ARGS(dvnode, name, fid), TP_STRUCT__entry( __field_struct(struct afs_fid, dfid ) @@ -928,13 +928,7 @@ TRACE_EVENT(afs_lookup, TP_fast_assign( int __len = min_t(int, name->len, 23); __entry->dfid = dvnode->fid; - if (vnode) { - __entry->fid = vnode->fid; - } else { - __entry->fid.vid = 0; - __entry->fid.vnode = 0; - __entry->fid.unique = 0; - } + __entry->fid = *fid; memcpy(__entry->name, name->name, __len); __entry->name[__len] = 0; ), |