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From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org
cc: Anastasia Belova <abelova@astralinux.ru>,
    Marc Dionne <marc.dionne@auristor.com>, dhowells@redhat.com,
    linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org,
    linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org
Subject: [PATCH] afs: Fix overwriting of result of DNS query
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Content-ID: <1842327.1703171371.1@warthog.procyon.org.uk>
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Date: Thu, 21 Dec 2023 15:09:31 +0000
Message-ID: <1842328.1703171371@warthog.procyon.org.uk>

Hi Linus,

Could you apply this fix, please?

Thanks,
David
---

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 o=
n
a patch from Anastasia Belova[1].

Fixes: d5c32c89b208 ("afs: Fix cell DNS lookup")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Anastasia Belova <abelova@astralinux.ru>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: lvc-project@linuxtesting.org
Link: https://lore.kernel.org/r/20231221085849.1463-1-abelova@astralinux.r=
u/ [1]
Link: https://lore.kernel.org/r/1700862.1703168632@warthog.procyon.org.uk/=
 # v1
---
 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 988c2ac7cece..926cb1188eba 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -409,10 +409,12 @@ static int afs_update_cell(struct afs_cell *cell)
 		if (ret =3D=3D -ENOMEM)
 			goto out_wake;
 =

-		ret =3D -ENOMEM;
 		vllist =3D afs_alloc_vlserver_list(0);
-		if (!vllist)
+		if (!vllist) {
+			if (ret >=3D 0)
+				ret =3D -ENOMEM;
 			goto out_wake;
+		}
 =

 		switch (ret) {
 		case -ENODATA: