From 6c784288f58583c9fe69e23a7c865337ffb292c0 Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@kernel.org>
Date: Tue, 11 Mar 2025 08:51:19 +0900
Subject: [PATCH] fs/proc/kcore.c: Clear ret value in read_kcore_iter after
 successful iov_iter_zero

BugLink: https://bugs.launchpad.net/bugs/2101915

commit 088f294609d8f8816dc316681aef2eb61982e0da upstream.

If iov_iter_zero succeeds after failed copy_from_kernel_nofault,
we need to reset the ret value to zero otherwise it will be returned
as final return value of read_kcore_iter.

This fixes objdump -d dump over /proc/kcore for me.

Cc: stable@vger.kernel.org
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20241121231118.3212000-1-jolsa@kernel.org
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 fs/proc/kcore.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 76f93693f704..0860911ca1ba 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -600,6 +600,7 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
 					ret = -EFAULT;
 					goto out;
 				}
+				ret = 0;
 			/*
 			 * We know the bounce buffer is safe to copy from, so
 			 * use _copy_to_iter() directly.