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authorAurelien Aptel <aaptel@suse.com>2019-12-04 16:14:54 +0100
committerSteve French <stfrench@microsoft.com>2019-12-04 11:51:18 -0600
commit9a7d5a9e6d7921e1854b4606ce8c3e17d565f463 (patch)
treee3bd912be7c3025e3586954802d59f222504579f /fs
parent3345bb44bacd99413a3dc0dcd9a99449d88d4dda (diff)
downloadlinux-9a7d5a9e6d7921e1854b4606ce8c3e17d565f463.tar.bz2
cifs: fix possible uninitialized access and race on iface_list
iface[0] was accessed regardless of the count value and without locking. * check count before accessing any ifaces * make copy of iface list (it's a simple POD array) and use it without locking. Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Diffstat (limited to 'fs')
-rw-r--r--fs/cifs/sess.c29
1 files changed, 26 insertions, 3 deletions
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index d95137304224..f0795c856d8f 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -77,6 +77,8 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
int i = 0;
int rc = 0;
int tries = 0;
+ struct cifs_server_iface *ifaces = NULL;
+ size_t iface_count;
if (left <= 0) {
cifs_dbg(FYI,
@@ -91,6 +93,26 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
}
/*
+ * Make a copy of the iface list at the time and use that
+ * instead so as to not hold the iface spinlock for opening
+ * channels
+ */
+ spin_lock(&ses->iface_lock);
+ iface_count = ses->iface_count;
+ if (iface_count <= 0) {
+ spin_unlock(&ses->iface_lock);
+ cifs_dbg(FYI, "no iface list available to open channels\n");
+ return 0;
+ }
+ ifaces = kmemdup(ses->iface_list, iface_count*sizeof(*ifaces),
+ GFP_ATOMIC);
+ if (!ifaces) {
+ spin_unlock(&ses->iface_lock);
+ return 0;
+ }
+ spin_unlock(&ses->iface_lock);
+
+ /*
* Keep connecting to same, fastest, iface for all channels as
* long as its RSS. Try next fastest one if not RSS or channel
* creation fails.
@@ -105,9 +127,9 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
break;
}
- iface = &ses->iface_list[i];
+ iface = &ifaces[i];
if (is_ses_using_iface(ses, iface) && !iface->rss_capable) {
- i = (i+1) % ses->iface_count;
+ i = (i+1) % iface_count;
continue;
}
@@ -115,7 +137,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
if (rc) {
cifs_dbg(FYI, "failed to open extra channel on iface#%d rc=%d\n",
i, rc);
- i = (i+1) % ses->iface_count;
+ i = (i+1) % iface_count;
continue;
}
@@ -124,6 +146,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
left--;
}
+ kfree(ifaces);
return ses->chan_count - old_chan_count;
}