From: Namjae Jeon <linkinjeon@kernel.org> mainline inclusion from mainline-v6.4-rc6 commit f1a411873c85b642f13b01f21b534c2bab81fc1b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7LU2Q CVE: CVE-2023-38427 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs... -------------------------------- 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> Conflict: fs/smb/server/smb2pdu.c Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- fs/ksmbd/smb2pdu.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 18e176fcddf0..c357b2127774 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -978,13 +978,13 @@ 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); @@ -1002,7 +1002,7 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn, if (len_of_ctxts == 0) break; - 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); @@ -1053,9 +1053,8 @@ 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 = (clen + sizeof(struct smb2_neg_context) + 7) & ~0x7; + len_of_ctxts -= offset; } return status; } -- 2.31.1