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Paulo Alcantarajohn-cabaj
Paulo Alcantara
authored and
john-cabaj
committed
cifs: fix NULL ptr dereference in refresh_mounts()
BugLink: https://bugs.launchpad.net/bugs/1970977 Either mount(2) or automount might not have server->origin_fullpath set yet while refresh_cache_worker() is attempting to refresh DFS referrals. Add missing NULL check and locking around it. This fixes bellow crash: [ 1070.276835] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 1070.277676] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 1070.278219] CPU: 1 PID: 8506 Comm: kworker/u8:1 Not tainted 5.18.0-rc3 #10 [ 1070.278701] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 [ 1070.279495] Workqueue: cifs-dfscache refresh_cache_worker [cifs] [ 1070.280044] RIP: 0010:strcasecmp+0x34/0x150 [ 1070.280359] Code: 00 00 00 fc ff df 41 54 55 48 89 fd 53 48 83 ec 10 eb 03 4c 89 fe 48 89 ef 48 83 c5 01 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 08 84 c0 0f 85 bc 00 00 00 0f b6 45 ff 44 [ 1070.281729] RSP: 0018:ffffc90008367958 EFLAGS: 00010246 [ 1070.282114] RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 [ 1070.282691] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1070.283273] RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff873eda27 [ 1070.283857] R10: ffffc900083679a0 R11: 0000000000000001 R12: ffff88812624c000 [ 1070.284436] R13: dffffc0000000000 R14: ffff88810e6e9a88 R15: ffff888119bb9000 [ 1070.284990] FS: 0000000000000000(0000) GS:ffff888151200000(0000) knlGS:0000000000000000 [ 1070.285625] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1070.286100] CR2: 0000561a4d922418 CR3: 000000010aecc000 CR4: 0000000000350ee0 [ 1070.286683] Call Trace: [ 1070.286890] <TASK> [ 1070.287070] refresh_cache_worker+0x895/0xd20 [cifs] [ 1070.287475] ? __refresh_tcon.isra.0+0xfb0/0xfb0 [cifs] [ 1070.287905] ? __lock_acquire+0xcd1/0x6960 [ 1070.288247] ? is_dynamic_key+0x1a0/0x1a0 [ 1070.288591] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 1070.289012] ? lock_downgrade+0x6f0/0x6f0 [ 1070.289318] process_one_work+0x7bd/0x12d0 [ 1070.289637] ? worker_thread+0x160/0xec0 [ 1070.289970] ? pwq_dec_nr_in_flight+0x230/0x230 [ 1070.290318] ? _raw_spin_lock_irq+0x5e/0x90 [ 1070.290619] worker_thread+0x5ac/0xec0 [ 1070.290891] ? process_one_work+0x12d0/0x12d0 [ 1070.291199] kthread+0x2a5/0x350 [ 1070.291430] ? kthread_complete_and_exit+0x20/0x20 [ 1070.291770] ret_from_fork+0x22/0x30 [ 1070.292050] </TASK> [ 1070.292223] Modules linked in: bpfilter cifs cifs_arc4 cifs_md4 [ 1070.292765] ---[ end trace 0000000000000000 ]--- [ 1070.293108] RIP: 0010:strcasecmp+0x34/0x150 [ 1070.293471] Code: 00 00 00 fc ff df 41 54 55 48 89 fd 53 48 83 ec 10 eb 03 4c 89 fe 48 89 ef 48 83 c5 01 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 08 84 c0 0f 85 bc 00 00 00 0f b6 45 ff 44 [ 1070.297718] RSP: 0018:ffffc90008367958 EFLAGS: 00010246 [ 1070.298622] RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 [ 1070.299428] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 1070.300296] RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff873eda27 [ 1070.301204] R10: ffffc900083679a0 R11: 0000000000000001 R12: ffff88812624c000 [ 1070.301932] R13: dffffc0000000000 R14: ffff88810e6e9a88 R15: ffff888119bb9000 [ 1070.302645] FS: 0000000000000000(0000) GS:ffff888151200000(0000) knlGS:0000000000000000 [ 1070.303462] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1070.304131] CR2: 0000561a4d922418 CR3: 000000010aecc000 CR4: 0000000000350ee0 [ 1070.305004] Kernel panic - not syncing: Fatal exception [ 1070.305711] Kernel Offset: disabled [ 1070.305971] ---[ end Kernel panic - not syncing: Fatal exception ]--- Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Cc: stable@vger.kernel.org Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com> (cherry picked from commit 41f1008) Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Acked-by: Philip Cox <philip.cox@canonical.com> Acked-by: Joseph Salisbury <joseph.salisbury@canonical.com> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
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lines changed

‎fs/cifs/connect.c

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3705,9 +3705,11 @@ static void setup_server_referral_paths(struct mount_ctx *mnt_ctx)
37053705
{
37063706
struct TCP_Server_Info *server = mnt_ctx->server;
37073707

3708+
mutex_lock(&server->refpath_lock);
37083709
server->origin_fullpath = mnt_ctx->origin_fullpath;
37093710
server->leaf_fullpath = mnt_ctx->leaf_fullpath;
37103711
server->current_fullpath = mnt_ctx->leaf_fullpath;
3712+
mutex_unlock(&server->refpath_lock);
37113713
mnt_ctx->origin_fullpath = mnt_ctx->leaf_fullpath = NULL;
37123714
}
37133715

‎fs/cifs/dfs_cache.c

Lines changed: 12 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1426,12 +1426,14 @@ static int refresh_tcon(struct cifs_ses **sessions, struct cifs_tcon *tcon, bool
14261426
struct TCP_Server_Info *server = tcon->ses->server;
14271427

14281428
mutex_lock(&server->refpath_lock);
1429-
if (strcasecmp(server->leaf_fullpath, server->origin_fullpath))
1430-
__refresh_tcon(server->leaf_fullpath + 1, sessions, tcon, force_refresh);
1429+
if (server->origin_fullpath) {
1430+
if (server->leaf_fullpath && strcasecmp(server->leaf_fullpath,
1431+
server->origin_fullpath))
1432+
__refresh_tcon(server->leaf_fullpath + 1, sessions, tcon, force_refresh);
1433+
__refresh_tcon(server->origin_fullpath + 1, sessions, tcon, force_refresh);
1434+
}
14311435
mutex_unlock(&server->refpath_lock);
14321436

1433-
__refresh_tcon(server->origin_fullpath + 1, sessions, tcon, force_refresh);
1434-
14351437
return 0;
14361438
}
14371439

@@ -1534,11 +1536,14 @@ static void refresh_mounts(struct cifs_ses **sessions)
15341536
list_del_init(&tcon->ulist);
15351537

15361538
mutex_lock(&server->refpath_lock);
1537-
if (strcasecmp(server->leaf_fullpath, server->origin_fullpath))
1538-
__refresh_tcon(server->leaf_fullpath + 1, sessions, tcon, false);
1539+
if (server->origin_fullpath) {
1540+
if (server->leaf_fullpath && strcasecmp(server->leaf_fullpath,
1541+
server->origin_fullpath))
1542+
__refresh_tcon(server->leaf_fullpath + 1, sessions, tcon, false);
1543+
__refresh_tcon(server->origin_fullpath + 1, sessions, tcon, false);
1544+
}
15391545
mutex_unlock(&server->refpath_lock);
15401546

1541-
__refresh_tcon(server->origin_fullpath + 1, sessions, tcon, false);
15421547
cifs_put_tcon(tcon);
15431548
}
15441549
}

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