From 8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b Mon Sep 17 00:00:00 2001
From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 13 Jul 2021 17:49:23 +0200
Subject: [PATCH] seq_file: disallow extremely large seq buffer allocations
Git-commit: 8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b
Patch-mainline: v5.14-rc3
References: bsc#1188062, CVE-2021-33909
There is no reasonable need for a buffer larger than this, and it avoids
int overflow pitfalls.
Fixes: 058504edd026 ("fs/seq_file: fallback to vmalloc allocation")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/seq_file.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index b117b212ef28..4a2cda04d3e2 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -32,6 +32,9 @@ static void seq_set_overflow(struct seq_file *m)
static void *seq_buf_alloc(unsigned long size)
{
+ if (unlikely(size > MAX_RW_COUNT))
+ return NULL;
+
return kvmalloc(size, GFP_KERNEL);
}
--
2.26.2