Commit 9a7d5a9e authored by Aurelien Aptel's avatar Aurelien Aptel Committed by Steve French

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: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Reviewed-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
parent 3345bb44
...@@ -77,6 +77,8 @@ int cifs_try_adding_channels(struct cifs_ses *ses) ...@@ -77,6 +77,8 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
int i = 0; int i = 0;
int rc = 0; int rc = 0;
int tries = 0; int tries = 0;
struct cifs_server_iface *ifaces = NULL;
size_t iface_count;
if (left <= 0) { if (left <= 0) {
cifs_dbg(FYI, cifs_dbg(FYI,
...@@ -90,6 +92,26 @@ int cifs_try_adding_channels(struct cifs_ses *ses) ...@@ -90,6 +92,26 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
return 0; return 0;
} }
/*
* 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 * Keep connecting to same, fastest, iface for all channels as
* long as its RSS. Try next fastest one if not RSS or channel * long as its RSS. Try next fastest one if not RSS or channel
...@@ -105,9 +127,9 @@ int cifs_try_adding_channels(struct cifs_ses *ses) ...@@ -105,9 +127,9 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
break; break;
} }
iface = &ses->iface_list[i]; iface = &ifaces[i];
if (is_ses_using_iface(ses, iface) && !iface->rss_capable) { if (is_ses_using_iface(ses, iface) && !iface->rss_capable) {
i = (i+1) % ses->iface_count; i = (i+1) % iface_count;
continue; continue;
} }
...@@ -115,7 +137,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses) ...@@ -115,7 +137,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
if (rc) { if (rc) {
cifs_dbg(FYI, "failed to open extra channel on iface#%d rc=%d\n", cifs_dbg(FYI, "failed to open extra channel on iface#%d rc=%d\n",
i, rc); i, rc);
i = (i+1) % ses->iface_count; i = (i+1) % iface_count;
continue; continue;
} }
...@@ -124,6 +146,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses) ...@@ -124,6 +146,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
left--; left--;
} }
kfree(ifaces);
return ses->chan_count - old_chan_count; return ses->chan_count - old_chan_count;
} }
......
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