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Backport few dfs related fixes to cifs

PATCH Superseded Rishabh Bhatnagar 2 participants 6 messages Jun 7, 2023

Subsystems (3)
Stable branch SMB client (CIFS) Kernel SMB3 server (ksmbd)

v1 of 2 Superseded Latest is v2 →

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Rishabh Bhatnagar

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#0 lore raw

cover Backport few dfs related fixes to cifs

Recently we have been seeing kernel panic in cifs_reconnect function while accessing tgt_list. Looks like tgt_list is not initialized correctly. There are fixes already present in 5.10 and later trees. Backporting them to 5.4

CIFS VFS: \\172.30.1.14 cifs_reconnect: no target servers for DFS failover

 BUG: unable to handle page fault for address: fffffffffffffff8
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 260e067 P4D 260e067 PUD 2610067 PMD 0
 Oops: 0000 [#1] SMP PTI
 RIP: 0010:cifs_reconnect+0x51d/0xef0 [cifs]
 RSP: 0018:ffffc90000693da0 EFLAGS: 00010282
 RAX: fffffffffffffff8 RBX: ffff8887fa63b800 RCX: fffffffffffffff8
 Call Trace:
 cifs_handle_standard+0x18d/0x1b0 [cifs]
 cifs_demultiplex_thread+0xa5c/0xc90 [cifs]
 kthread+0x113/0x130

*** BLURB HERE ***

Paulo Alcantara (2):
cifs: get rid of unused parameter in reconn_setup_dfs_targets()
cifs: handle empty list of targets in cifs_reconnect()

 fs/cifs/connect.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)
Signature · 1 line
2.39.2
author
#1 lore raw

PATCH 1/2 cifs: get rid of unused parameter in reconn_setup_dfs_targets()

From: Paulo Alcantara <[email protected]>

commit baf3f08ef4083b76ca67b143e135213a7f941879 upstream.

The target iterator parameter "it" is not used in reconn_setup_dfs_targets(), so just remove it.

Signed-off-by Paulo Alcantara (SUSE) <[email protected]>
Reviewed-by Aurelien Aptel <[email protected]>
Signed-off-by Steve French <[email protected]>
Signed-off-by Rishabh Bhatnagar <[email protected]>
---
 fs/cifs/connect.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
fs/cifs/connect.c +2 -3
index 6c8dd7c0b83a..b5cd3dc479ce 100644
@@ -469,8 +469,7 @@ static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
 }
 
 static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
-					   struct dfs_cache_tgt_list *tl,
-					   struct dfs_cache_tgt_iterator **it)
+					   struct dfs_cache_tgt_list *tl)
 {
 	if (!cifs_sb->origin_fullpath)
 		return -EOPNOTSUPP;

@@ -515,7 +514,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
 	} else {
 		cifs_sb = CIFS_SB(sb);
 
-		rc = reconn_setup_dfs_targets(cifs_sb, &tgt_list, &tgt_it);
+		rc = reconn_setup_dfs_targets(cifs_sb, &tgt_list);
 		if (rc && (rc != -EOPNOTSUPP)) {
 			cifs_server_dbg(VFS, "%s: no target servers for DFS failover\n",
 				 __func__);
Signature · 1 line
2.39.2
author
#2 lore raw

PATCH 2/2 cifs: handle empty list of targets in cifs_reconnect()

In reply to Rishabh Bhatnagar

From: Paulo Alcantara <[email protected]>

commit a52930353eaf443489a350a135c5525a4acbbf56 upstream.

In case there were no cached DFS referrals in reconn_setup_dfs_targets(), set cifs_sb to NULL prior to calling reconn_set_next_dfs_target() so it would not try to access an empty tgt_list.

Signed-off-by Paulo Alcantara (SUSE) <[email protected]>
Reviewed-by Aurelien Aptel <[email protected]>
Signed-off-by Steve French <[email protected]>
Signed-off-by Rishabh Bhatnagar <[email protected]>
---
 fs/cifs/connect.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
fs/cifs/connect.c +6 -4
index b5cd3dc479ce..d8d9d9061544 100644
@@ -513,11 +513,13 @@ cifs_reconnect(struct TCP_Server_Info *server)
 		sb = NULL;
 	} else {
 		cifs_sb = CIFS_SB(sb);
-
 		rc = reconn_setup_dfs_targets(cifs_sb, &tgt_list);
-		if (rc && (rc != -EOPNOTSUPP)) {
-			cifs_server_dbg(VFS, "%s: no target servers for DFS failover\n",
-				 __func__);
+		if (rc) {
+			cifs_sb = NULL;
+			if (rc != -EOPNOTSUPP) {
+				cifs_server_dbg(VFS, "%s: no target servers for DFS failover\n",
+						__func__);
+			}
 		} else {
 			server->nr_targets = dfs_cache_get_nr_tgts(&tgt_list);
 		}
Signature · 1 line
2.39.2
maintainer
#3 lore raw
In reply to Rishabh Bhatnagar
Quoted 20 lines · Rishabh Bhatnagar

Recently we have been seeing kernel panic in cifs_reconnect function while accessing tgt_list. Looks like tgt_list is not initialized correctly. There are fixes already present in 5.10 and later trees. Backporting them to 5.4

CIFS VFS: \\172.30.1.14 cifs_reconnect: no target servers for DFS failover

 BUG: unable to handle page fault for address: fffffffffffffff8
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 260e067 P4D 260e067 PUD 2610067 PMD 0
 Oops: 0000 [#1] SMP PTI
 RIP: 0010:cifs_reconnect+0x51d/0xef0 [cifs]
 RSP: 0018:ffffc90000693da0 EFLAGS: 00010282
 RAX: fffffffffffffff8 RBX: ffff8887fa63b800 RCX: fffffffffffffff8
 Call Trace:
 cifs_handle_standard+0x18d/0x1b0 [cifs]
 cifs_demultiplex_thread+0xa5c/0xc90 [cifs]
 kthread+0x113/0x130
Quoted 1 line

*** BLURB HERE ***

No blurb?

And this says 5.4, yet your patches say 5.10?

Totally confused...

greg k-h

author
#4 lore raw
Quoted 25 lines · Greg KH

CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.

Quoted 20 lines · Rishabh Bhatnagar

Recently we have been seeing kernel panic in cifs_reconnect function while accessing tgt_list. Looks like tgt_list is not initialized correctly. There are fixes already present in 5.10 and later trees. Backporting them to 5.4

CIFS VFS: \\172.30.1.14 cifs_reconnect: no target servers for DFS failover

  BUG: unable to handle page fault for address: fffffffffffffff8
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 260e067 P4D 260e067 PUD 2610067 PMD 0
  Oops: 0000 [#1] SMP PTI
  RIP: 0010:cifs_reconnect+0x51d/0xef0 [cifs]
  RSP: 0018:ffffc90000693da0 EFLAGS: 00010282
  RAX: fffffffffffffff8 RBX: ffff8887fa63b800 RCX: fffffffffffffff8
  Call Trace:
  cifs_handle_standard+0x18d/0x1b0 [cifs]
  cifs_demultiplex_thread+0xa5c/0xc90 [cifs]
  kthread+0x113/0x130
Quoted 8 lines
Quoted 1 line

*** BLURB HERE ***

No blurb?

And this says 5.4, yet your patches say 5.10?

Totally confused...

greg k-h

These patches are applicable for 5.4. Will send another version with that fixed. Apologies for the mess.

maintainer
#5 lore raw
Quoted 32 lines · Rishabh
Quoted 30 lines · Greg KH

CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.

Quoted 20 lines · Rishabh Bhatnagar

Recently we have been seeing kernel panic in cifs_reconnect function while accessing tgt_list. Looks like tgt_list is not initialized correctly. There are fixes already present in 5.10 and later trees. Backporting them to 5.4

CIFS VFS: \\172.30.1.14 cifs_reconnect: no target servers for DFS failover

  BUG: unable to handle page fault for address: fffffffffffffff8
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 260e067 P4D 260e067 PUD 2610067 PMD 0
  Oops: 0000 [#1] SMP PTI
  RIP: 0010:cifs_reconnect+0x51d/0xef0 [cifs]
  RSP: 0018:ffffc90000693da0 EFLAGS: 00010282
  RAX: fffffffffffffff8 RBX: ffff8887fa63b800 RCX: fffffffffffffff8
  Call Trace:
  cifs_handle_standard+0x18d/0x1b0 [cifs]
  cifs_demultiplex_thread+0xa5c/0xc90 [cifs]
  kthread+0x113/0x130
Quoted 1 line

*** BLURB HERE ***

No blurb?

And this says 5.4, yet your patches say 5.10?

Quoted 7 lines
Quoted 3 lines

Totally confused...

greg k-h

These patches are applicable for 5.4. Will send another version with that fixed.
Apologies for the mess.

Please resend both series, as this one I already dropped from my queue.

thanks,

greg k-h