linux-kernel - [PATCH 1/2] mm/huge_memory: skip invalid debugfs file entry for folio split

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Wed, 24 Apr 2024 15:54:48 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: akpm@...ux-foundation.org,
	ziy@...dia.com,
	linux-mm@...ck.org
Cc: fstests@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	willy@...radead.org,
	hare@...e.de,
	john.g.garry@...cle.com,
	p.raghav@...sung.com,
	da.gomez@...sung.com,
	mcgrof@...nel.org
Subject: [PATCH 1/2] mm/huge_memory: skip invalid debugfs file entry for folio split

If the file entry is too long we may easily end up going out of bounds
and crash after strsep() on sscanf(). To avoid this ensure we bound the
string to an expected length before we use sscanf() on it.

Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 mm/huge_memory.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9e9879d2f501..8386d24a163e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3623,6 +3623,7 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
 		char file_path[MAX_INPUT_BUF_SZ];
 		pgoff_t off_start = 0, off_end = 0;
 		size_t input_len = strlen(input_buf);
+		size_t max_left_over;
 
 		tok = strsep(&buf, ",");
 		if (tok) {
@@ -3632,6 +3633,14 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
 			goto out;
 		}
 
+		max_left_over = MAX_INPUT_BUF_SZ - strlen(file_path);
+		if (!buf ||
+		    strnlen(buf, max_left_over) < 7 ||
+		    strnlen(buf, max_left_over) > max_left_over) {
+			ret = -EINVAL;
+			goto out;
+		}
+
 		ret = sscanf(buf, "0x%lx,0x%lx,%d", &off_start, &off_end, &new_order);
 		if (ret != 2 && ret != 3) {
 			ret = -EINVAL;
-- 
2.43.0