linux-kernel - [PATCH] vfs: calculate seek offsets using unsigned variables

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:	Mon,  1 Dec 2014 23:04:07 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	linux-kernel@...r.kernel.org
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH] vfs: calculate seek offsets using unsigned variables

Adding two loff_ts means adding two signed integers. Adding two such integers
when they are unchecked might cause an overflow which is undefined for
signed integers.

Avoid it by doing the math using unsigned cast and casting it back implicitly
into loff_t.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 fs/read_write.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index c0805c9..54311f4 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -91,7 +91,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
 {
 	switch (whence) {
 	case SEEK_END:
-		offset += eof;
+		offset += (u64)eof;
 		break;
 	case SEEK_CUR:
 		/*
@@ -108,7 +108,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
 		 * like SEEK_SET.
 		 */
 		spin_lock(&file->f_lock);
-		offset = vfs_setpos(file, file->f_pos + offset, maxsize);
+		offset = vfs_setpos(file, (u64)file->f_pos + offset, maxsize);
 		spin_unlock(&file->f_lock);
 		return offset;
 	case SEEK_DATA:
-- 
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/