This bug is in parse_lease_state, and it is caused by the missing check
of `struct create_context`. When the ksmbd traverses the create_contexts,
it doesn't check if the field of `NameOffset` and `Next` is valid,
The KASAN message is following:
[ 6.664323] BUG: KASAN: slab-out-of-bounds in parse_lease_state+0x7d/0x280
[ 6.664738] Read of size 2 at addr ffff888005c08988 by task kworker/0:3/103
...
[ 6.666644] Call Trace:
[ 6.666796] <TASK>
[ 6.666933] dump_stack_lvl+0x33/0x50
[ 6.667167] print_report+0xcc/0x620
[ 6.667903] kasan_report+0xae/0xe0
[ 6.668374] kasan_check_range+0x35/0x1b0
[ 6.668621] parse_lease_state+0x7d/0x280
[ 6.668868] smb2_open+0xbe8/0x4420
[ 6.675137] handle_ksmbd_work+0x282/0x820
Use smb2_find_context_vals() to find smb2 create request lease context.
smb2_find_context_vals validate create context fields.
Reported-by: Chih-Yen Chang <cc85nod@xxxxxxxxx>
Tested-by: Chih-Yen Chang <cc85nod@xxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
---
fs/smb/server/oplock.c | 66 +++++++++++++++---------------------------
1 file changed, 24 insertions(+), 42 deletions(-)
diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c
index db181bdad73a..844b303baf29 100644
--- a/fs/smb/server/oplock.c
+++ b/fs/smb/server/oplock.c
@@ -1415,56 +1415,38 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
*/
struct lease_ctx_info *parse_lease_state(void *open_req)
{
- char *data_offset;
struct create_context *cc;
- unsigned int next = 0;
- char *name;
- bool found = false;
struct smb2_create_req *req = (struct smb2_create_req *)open_req;
- struct lease_ctx_info *lreq = kzalloc(sizeof(struct lease_ctx_info),
- GFP_KERNEL);
+ struct lease_ctx_info *lreq;
+
+ cc = smb2_find_context_vals(req, SMB2_CREATE_REQUEST_LEASE, 4);
+ if (IS_ERR_OR_NULL(cc))
+ return NULL;
+
+ lreq = kzalloc(sizeof(struct lease_ctx_info), GFP_KERNEL);
if (!lreq)
return NULL;
- data_offset = (char *)req + le32_to_cpu(req->CreateContextsOffset);
- cc = (struct create_context *)data_offset;
- do {
- cc = (struct create_context *)((char *)cc + next);
- name = le16_to_cpu(cc->NameOffset) + (char *)cc;
- if (le16_to_cpu(cc->NameLength) != 4 ||
- strncmp(name, SMB2_CREATE_REQUEST_LEASE, 4)) {
- next = le32_to_cpu(cc->Next);
- continue;
- }
- found = true;
- break;
- } while (next != 0);
+ if (sizeof(struct lease_context_v2) == le32_to_cpu(cc->DataLength)) {
+ struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
- if (found) {
- if (sizeof(struct lease_context_v2) == le32_to_cpu(cc->DataLength)) {
- struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
-
- memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
- lreq->req_state = lc->lcontext.LeaseState;
- lreq->flags = lc->lcontext.LeaseFlags;
- lreq->duration = lc->lcontext.LeaseDuration;
- memcpy(lreq->parent_lease_key, lc->lcontext.ParentLeaseKey,
- SMB2_LEASE_KEY_SIZE);
- lreq->version = 2;
- } else {
- struct create_lease *lc = (struct create_lease *)cc;
+ memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
+ lreq->req_state = lc->lcontext.LeaseState;
+ lreq->flags = lc->lcontext.LeaseFlags;
+ lreq->duration = lc->lcontext.LeaseDuration;
+ memcpy(lreq->parent_lease_key, lc->lcontext.ParentLeaseKey,
+ SMB2_LEASE_KEY_SIZE);
+ lreq->version = 2;
+ } else {
+ struct create_lease *lc = (struct create_lease *)cc;
- memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
- lreq->req_state = lc->lcontext.LeaseState;
- lreq->flags = lc->lcontext.LeaseFlags;
- lreq->duration = lc->lcontext.LeaseDuration;
- lreq->version = 1;
- }
- return lreq;
+ memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
+ lreq->req_state = lc->lcontext.LeaseState;
+ lreq->flags = lc->lcontext.LeaseFlags;
+ lreq->duration = lc->lcontext.LeaseDuration;
+ lreq->version = 1;
}
-
- kfree(lreq);
- return NULL;
+ return lreq;
}
/**
--
2.25.1
