From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
commit f1a411873c85b642f13b01f21b534c2bab81fc1b upstream.
The check in the beginning is
`clen + sizeof(struct smb2_neg_context) <= len_of_ctxts`,
but in the end of loop, `len_of_ctxts` will subtract
`((clen + 7) & ~0x7) + sizeof(struct smb2_neg_context)`, which causes
integer underflow when clen does the 8 alignment. We should use
`(clen + 7) & ~0x7` in the check to avoid underflow from happening.
Then there are some variables that need to be declared unsigned
instead of signed.
[ 11.671070] BUG: KASAN: slab-out-of-bounds in smb2_handle_negotiate+0x799/0x1610
[ 11.671533] Read of size 2 at addr ffff888005e86cf2 by task kworker/0:0/7
...
[ 11.673383] Call Trace:
[ 11.673541] <TASK>
[ 11.673679] dump_stack_lvl+0x33/0x50
[ 11.673913] print_report+0xcc/0x620
[ 11.674671] kasan_report+0xae/0xe0
[ 11.675171] kasan_check_range+0x35/0x1b0
[ 11.675412] smb2_handle_negotiate+0x799/0x1610
[ 11.676217] ksmbd_smb_negotiate_common+0x526/0x770
[ 11.676795] handle_ksmbd_work+0x274/0x810
...
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Chih-Yen Chang <cc85nod@xxxxxxxxx>
Tested-by: Chih-Yen Chang <cc85nod@xxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ksmbd/smb2pdu.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -991,13 +991,13 @@ static void decode_sign_cap_ctxt(struct
static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
struct smb2_negotiate_req *req,
- int len_of_smb)
+ unsigned int len_of_smb)
{
/* +4 is to account for the RFC1001 len field */
struct smb2_neg_context *pctx = (struct smb2_neg_context *)req;
int i = 0, len_of_ctxts;
- int offset = le32_to_cpu(req->NegotiateContextOffset);
- int neg_ctxt_cnt = le16_to_cpu(req->NegotiateContextCount);
+ unsigned int offset = le32_to_cpu(req->NegotiateContextOffset);
+ unsigned int neg_ctxt_cnt = le16_to_cpu(req->NegotiateContextCount);
__le32 status = STATUS_INVALID_PARAMETER;
ksmbd_debug(SMB, "decoding %d negotiate contexts\n", neg_ctxt_cnt);
@@ -1011,7 +1011,7 @@ static __le32 deassemble_neg_contexts(st
while (i++ < neg_ctxt_cnt) {
int clen, ctxt_len;
- if (len_of_ctxts < sizeof(struct smb2_neg_context))
+ if (len_of_ctxts < (int)sizeof(struct smb2_neg_context))
break;
pctx = (struct smb2_neg_context *)((char *)pctx + offset);
@@ -1066,9 +1066,8 @@ static __le32 deassemble_neg_contexts(st
}
/* offsets must be 8 byte aligned */
- clen = (clen + 7) & ~0x7;
- offset = clen + sizeof(struct smb2_neg_context);
- len_of_ctxts -= clen + sizeof(struct smb2_neg_context);
+ offset = (ctxt_len + 7) & ~0x7;
+ len_of_ctxts -= offset;
}
return status;
}
