6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pengpeng Hou <redacted>
commit 95540462e630edbc8504e9537d16453d6942d143 upstream.
ecryptfs_miscdev_write() accepts the minimum one-byte packet-length
encoding, but always copies the maximum two-byte encoding from userspace
before parsing it. A six-byte message therefore reads one byte beyond the
submitted user buffer.
Zero-initialize the peek buffer and copy only the packet-length bytes
present. The existing exact packet-size check still rejects truncated
two-byte encodings after the parser determines their encoded length.
Fixes: 8bf2debd5f7b ("eCryptfs: introduce device handle for userspace daemon communications")
Cc: <redacted>
Signed-off-by: Pengpeng Hou <redacted>
Signed-off-by: Tyler Hicks <code@tyhicks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ecryptfs/miscdev.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -357,7 +357,7 @@ ecryptfs_miscdev_write(struct file *file
u32 seq;
size_t packet_size, packet_size_length;
char *data;
- unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
+ unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE] = { };
ssize_t rc;
if (count == 0) {@@ -373,7 +373,8 @@ ecryptfs_miscdev_write(struct file *file
}
if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
- sizeof(packet_size_peek))) {
+ min_t(size_t, count - PKT_LEN_OFFSET,
+ sizeof(packet_size_peek)))) {
printk(KERN_WARNING "%s: Error while inspecting packet size\n",
__func__);
return -EFAULT;