[lvc-project] [PATCH 5.10 20/75] afs: Fix overwriting of result of DNS query

[Greg Kroah-Hartman]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells at redhat.com>

[ Upstream commit a9e01ac8c5ff32669119c40dfdc9e80eb0b7d7aa ]

In afs_update_cell(), ret is the result of the DNS lookup and the errors
are to be handled by a switch - however, the value gets clobbered in
between by setting it to -ENOMEM in case afs_alloc_vlserver_list()
fails.

Fix this by moving the setting of -ENOMEM into the error handling for
OOM failure.  Further, only do it if we don't have an alternative error
to return.

Found by Linux Verification Center (linuxtesting.org) with SVACE.  Based
on a patch from Anastasia Belova [1].

Fixes: d5c32c89b208 ("afs: Fix cell DNS lookup")
Signed-off-by: David Howells <dhowells at redhat.com>
Reviewed-by: Jeffrey Altman <jaltman at auristor.com>
cc: Anastasia Belova <abelova at astralinux.ru>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: linux-afs at lists.infradead.org
cc: lvc-project at linuxtesting.org
Link: https://lore.kernel.org/r/20231221085849.1463-1-abelova@astralinux.ru/ [1]
Link: https://lore.kernel.org/r/1700862.1703168632@warthog.procyon.org.uk/ # v1
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 fs/afs/cell.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 887b673f62230..cfd3c4dabdb2c 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -407,10 +407,12 @@ static int afs_update_cell(struct afs_cell *cell)
 		if (ret == -ENOMEM)
 			goto out_wake;
 
-		ret = -ENOMEM;
 		vllist = afs_alloc_vlserver_list(0);
-		if (!vllist)
+		if (!vllist) {
+			if (ret >= 0)
+				ret = -ENOMEM;
 			goto out_wake;
+		}
 
 		switch (ret) {
 		case -ENODATA:
-- 
2.43.0