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authorNamjae Jeon <linkinjeon@kernel.org>2023-05-28 00:23:09 +0900
committerSteve French <stfrench@microsoft.com>2023-06-02 12:30:57 -0500
commitf1a411873c85b642f13b01f21b534c2bab81fc1b (patch)
treecaa7166af42776ef80dfa2c61ee0cf78ad881bc3 /fs
parent8828003759391029fc45c15ac346622cdae19b6d (diff)
ksmbd: fix out-of-bound read in deassemble_neg_contexts()
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@vger.kernel.org Signed-off-by: Chih-Yen Chang <cc85nod@gmail.com> Tested-by: Chih-Yen Chang <cc85nod@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/smb/server/smb2pdu.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 7a81541de602..25c0ba04c59d 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -963,13 +963,13 @@ static void decode_sign_cap_ctxt(struct ksmbd_conn *conn,
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);
@@ -983,7 +983,7 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
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);
@@ -1038,9 +1038,8 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
}
/* 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;
}