6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
commit eec04ea119691e65227a97ce53c0da6b9b74b0b7 upstream.
Fix potential OOB in receive_encrypted_standard() if server returned a
large shdr->NextCommand that would end up writing off the end of
@next_buffer.
Fixes: b24df3e30cbf ("cifs: update receive_encrypted_standard to handle compounded responses")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Robert Morris <rtm@xxxxxxxxxxxxx>
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/smb/client/smb2ops.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -4941,6 +4941,7 @@ receive_encrypted_standard(struct TCP_Se
struct smb2_hdr *shdr;
unsigned int pdu_length = server->pdu_size;
unsigned int buf_size;
+ unsigned int next_cmd;
struct mid_q_entry *mid_entry;
int next_is_large;
char *next_buffer = NULL;
@@ -4969,14 +4970,15 @@ receive_encrypted_standard(struct TCP_Se
next_is_large = server->large_buf;
one_more:
shdr = (struct smb2_hdr *)buf;
- if (shdr->NextCommand) {
+ next_cmd = le32_to_cpu(shdr->NextCommand);
+ if (next_cmd) {
+ if (WARN_ON_ONCE(next_cmd > pdu_length))
+ return -1;
if (next_is_large)
next_buffer = (char *)cifs_buf_get();
else
next_buffer = (char *)cifs_small_buf_get();
- memcpy(next_buffer,
- buf + le32_to_cpu(shdr->NextCommand),
- pdu_length - le32_to_cpu(shdr->NextCommand));
+ memcpy(next_buffer, buf + next_cmd, pdu_length - next_cmd);
}
mid_entry = smb2_find_mid(server, buf);
@@ -5000,8 +5002,8 @@ one_more:
else
ret = cifs_handle_standard(server, mid_entry);
- if (ret == 0 && shdr->NextCommand) {
- pdu_length -= le32_to_cpu(shdr->NextCommand);
+ if (ret == 0 && next_cmd) {
+ pdu_length -= next_cmd;
server->large_buf = next_is_large;
if (next_is_large)
server->bigbuf = buf = next_buffer;
