TCP_Server_Info::hostname may be updated once or many times during reconnect, so protect its access outside reconnect path as well and then prevent any potential use-after-free bugs.
Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com --- fs/cifs/cifs_debug.c | 7 ++++++- fs/cifs/cifs_debug.h | 12 ++++++------ fs/cifs/connect.c | 10 +++++++--- fs/cifs/sess.c | 7 ++++--- 4 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c index e9c8c088d948..d4ed200a9471 100644 --- a/fs/cifs/cifs_debug.c +++ b/fs/cifs/cifs_debug.c @@ -280,8 +280,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v) seq_printf(m, "\n%d) ConnectionId: 0x%llx ", c, server->conn_id);
+ spin_lock(&server->srv_lock); if (server->hostname) seq_printf(m, "Hostname: %s ", server->hostname); + spin_unlock(&server->srv_lock); #ifdef CONFIG_CIFS_SMB_DIRECT if (!server->rdma) goto skip_rdma; @@ -623,10 +625,13 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v) server->fastest_cmd[j], server->slowest_cmd[j]); for (j = 0; j < NUMBER_OF_SMB2_COMMANDS; j++) - if (atomic_read(&server->smb2slowcmd[j])) + if (atomic_read(&server->smb2slowcmd[j])) { + spin_lock(&server->srv_lock); seq_printf(m, " %d slow responses from %s for command %d\n", atomic_read(&server->smb2slowcmd[j]), server->hostname, j); + spin_unlock(&server->srv_lock); + } #endif /* STATS2 */ list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) { list_for_each_entry(tcon, &ses->tcon_list, tcon_list) { diff --git a/fs/cifs/cifs_debug.h b/fs/cifs/cifs_debug.h index d44808263cfb..ce5cfd236fdb 100644 --- a/fs/cifs/cifs_debug.h +++ b/fs/cifs/cifs_debug.h @@ -81,19 +81,19 @@ do { \
#define cifs_server_dbg_func(ratefunc, type, fmt, ...) \ do { \ - const char *sn = ""; \ - if (server && server->hostname) \ - sn = server->hostname; \ + spin_lock(&server->srv_lock); \ if ((type) & FYI && cifsFYI & CIFS_INFO) { \ pr_debug_ ## ratefunc("%s: \\%s " fmt, \ - __FILE__, sn, ##__VA_ARGS__); \ + __FILE__, server->hostname, \ + ##__VA_ARGS__); \ } else if ((type) & VFS) { \ pr_err_ ## ratefunc("VFS: \\%s " fmt, \ - sn, ##__VA_ARGS__); \ + server->hostname, ##__VA_ARGS__); \ } else if ((type) & NOISY && (NOISY != 0)) { \ pr_debug_ ## ratefunc("\\%s " fmt, \ - sn, ##__VA_ARGS__); \ + server->hostname, ##__VA_ARGS__); \ } \ + spin_unlock(&server->srv_lock); \ } while (0)
#define cifs_server_dbg(type, fmt, ...) \ diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 1cbb90587995..eee8b31c1eaf 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -403,8 +403,10 @@ static int __reconnect_target_unlocked(struct TCP_Server_Info *server, const cha if (server->hostname != target) { hostname = extract_hostname(target); if (!IS_ERR(hostname)) { + spin_lock(&server->srv_lock); kfree(server->hostname); server->hostname = hostname; + spin_unlock(&server->srv_lock); } else { cifs_dbg(FYI, "%s: couldn't extract hostname or address from dfs target: %ld\n", __func__, PTR_ERR(hostname)); @@ -561,9 +563,7 @@ cifs_echo_request(struct work_struct *work) goto requeue_echo;
rc = server->ops->echo ? server->ops->echo(server) : -ENOSYS; - if (rc) - cifs_dbg(FYI, "Unable to send echo request to server: %s\n", - server->hostname); + cifs_server_dbg(FYI, "send echo request: rc = %d\n", rc);
/* Check witness registrations */ cifs_swn_check(); @@ -1404,6 +1404,8 @@ static int match_server(struct TCP_Server_Info *server, struct smb3_fs_context * { struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
+ lockdep_assert_held(&server->srv_lock); + if (ctx->nosharesock) return 0;
@@ -1810,7 +1812,9 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx) if (tcon == NULL) return -ENOMEM;
+ spin_lock(&server->srv_lock); scnprintf(unc, sizeof(unc), "\\%s\IPC$", server->hostname); + spin_unlock(&server->srv_lock);
xid = get_xid(); tcon->ses = ses; diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index d2cbae4b5d21..335c078c42fb 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -159,6 +159,7 @@ cifs_chan_is_iface_active(struct cifs_ses *ses, /* returns number of channels added */ int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses) { + struct TCP_Server_Info *server = ses->server; int old_chan_count, new_chan_count; int left; int rc = 0; @@ -178,16 +179,16 @@ int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses) return 0; }
- if (ses->server->dialect < SMB30_PROT_ID) { + if (server->dialect < SMB30_PROT_ID) { spin_unlock(&ses->chan_lock); cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.0 or above\n"); return 0; }
- if (!(ses->server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) { + if (!(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) { ses->chan_max = 1; spin_unlock(&ses->chan_lock); - cifs_dbg(VFS, "server %s does not support multichannel\n", ses->server->hostname); + cifs_server_dbg(VFS, "no multichannel support\n"); return 0; } spin_unlock(&ses->chan_lock);