From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 6 Jul 2021 17:56:03 +0000 (+0200)
Subject: [PATCH] seq_file: Disallow extremely large seq buffer allocations
X-Git-Tag: archive/raspbian/5.10.46-5+rpi1^2~44
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks:///%22http:/www.example.com/cgi/%22https:/%22bookmarks:/?a=commitdiff_plain;h=70cfb8f7762b9e40341583009e49c2b728eea254;p=linux.git

[PATCH] seq_file: Disallow extremely large seq buffer allocations

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")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name seq_file-Disallow-extremely-large-seq-buffer-allocat.patch
---

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 03a369ccd28..472714716be 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_ACCOUNT);
 }