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authorAl Viro <viro@zeniv.linux.org.uk>2012-01-10 22:24:48 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2012-01-11 00:19:58 -0500
commit8753333266be67ff3a984ac1f6566d31c260bee4 (patch)
tree27a8565988791e2971d631e19c7a9a0057386668
parent4041bcdc7bef06a2fb29c57394c713a74bd13b08 (diff)
downloadvexpress-lsk-8753333266be67ff3a984ac1f6566d31c260bee4.tar.gz
autofs4: catatonic_mode vs. notify_daemon race
we need to hold ->wq_mutex while we are forming the packet to send, lest we have autofs4_catatonic_mode() setting wq->name.name to NULL just as autofs4_notify_daemon() decides to memcpy() from it... We do have check for catatonic mode immediately after that (under ->wq_mutex, as it ought to be) and packet won't be actually sent, but it'll be too late for us if we oops on that memcpy() from NULL... Fix is obvious - just extend the area covered by ->wq_mutex over that switch and check whether it's catatonic *before* doing anything else. Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/autofs4/waitq.c25
1 files changed, 14 insertions, 11 deletions
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index c13273afd54..9a0256da5d5 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -110,6 +110,13 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
pkt.hdr.proto_version = sbi->version;
pkt.hdr.type = type;
+ mutex_lock(&sbi->wq_mutex);
+
+ /* Check if we have become catatonic */
+ if (sbi->catatonic) {
+ mutex_unlock(&sbi->wq_mutex);
+ return;
+ }
switch (type) {
/* Kernel protocol v4 missing and expire packets */
case autofs_ptype_missing:
@@ -163,22 +170,18 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
}
default:
printk("autofs4_notify_daemon: bad type %d!\n", type);
+ mutex_unlock(&sbi->wq_mutex);
return;
}
- /* Check if we have become catatonic */
- mutex_lock(&sbi->wq_mutex);
- if (!sbi->catatonic) {
- pipe = sbi->pipe;
- get_file(pipe);
- }
+ pipe = sbi->pipe;
+ get_file(pipe);
+
mutex_unlock(&sbi->wq_mutex);
- if (pipe) {
- if (autofs4_write(pipe, &pkt, pktsz))
- autofs4_catatonic_mode(sbi);
- fput(pipe);
- }
+ if (autofs4_write(pipe, &pkt, pktsz))
+ autofs4_catatonic_mode(sbi);
+ fput(pipe);
}
static int autofs4_getpath(struct autofs_sb_info *sbi,