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From:   Niels Dossche <dossche.niels@gmail.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Mina Almasry <almasrymina@google.com>,
        Niels Dossche <dossche.niels@gmail.com>
Subject: [PATCH 1/2] mm: mremap: fix sign for EFAULT error return value
Date:   Thu, 28 Apr 2022 00:44:38 +0200
Message-Id: <20220427224439.23828-2-dossche.niels@gmail.com>
In-Reply-To: <20220427224439.23828-1-dossche.niels@gmail.com>
References: <20220427224439.23828-1-dossche.niels@gmail.com>
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The mremap syscall is supposed to return a pointer to the new virtual
memory area on success, and a negative value of the error code in case
of failure. Currently, EFAULT is returned when the VMA is not found,
instead of -EFAULT. The users of this syscall will therefore believe
the syscall succeeded in case the VMA didn't exist, as it returns a
pointer to address 0xe (0xe being the value of EFAULT).
Fix the sign of the error value.

Fixes: 550a7d60bd5e ("mm, hugepages: add mremap() support for hugepage backed vma")
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
---
 mm/mremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 303d3290b938..0b93fac76851 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -947,7 +947,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 		return -EINTR;
 	vma = vma_lookup(mm, addr);
 	if (!vma) {
-		ret = EFAULT;
+		ret = -EFAULT;
 		goto out;
 	}
 
-- 
2.35.2