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ksmbd: fix credit charge calculation for SMB2 QUERY_INFO

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smb2_validate_credit_charge() computes the credit charge a request is
allowed to consume from the payload size:

  CreditCharge = (max(SendPayloadSize, ResponsePayloadSize) - 1)/65536 + 1

For SMB2 QUERY_INFO, the server must validate CreditCharge based on the
*maximum* of InputBufferLength and OutputBufferLength. ksmbd instead
summed the two lengths, which overestimates the required charge.

As a result a single-credit QUERY_INFO whose InputBufferLength and
OutputBufferLength each fit in 64KB but whose sum exceeds 64KB is
rejected with STATUS_INVALID_PARAMETER, even though it is a valid
request. IOCTL already uses max() of the request and response sizes;
make QUERY_INFO consistent by feeding InputBufferLength as the request
length and OutputBufferLength as the expected response length so that
smb2_validate_credit_charge() takes their maximum.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Namjae Jeon 2026-06-26 10:51:16 +09:00 committed by Steve French
parent 6b9a2e09d4
commit 284dc80ff5
1 changed files with 7 additions and 2 deletions
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9
fs/smb/server/smb2misc.c
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@ -261,8 +261,12 @@ static int smb2_calc_size(void *buf, unsigned int *len)
static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
{
return le32_to_cpu(h->InputBufferLength) +
le32_to_cpu(h->OutputBufferLength);
return le32_to_cpu(h->InputBufferLength);
}
static inline int smb2_query_info_resp_len(struct smb2_query_info_req *h)
{
return le32_to_cpu(h->OutputBufferLength);
}
static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
@ -308,6 +312,7 @@ static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
switch (hdr->Command) {
case SMB2_QUERY_INFO:
req_len = smb2_query_info_req_len(__hdr);
expect_resp_len = smb2_query_info_resp_len(__hdr);
break;
case SMB2_SET_INFO:
req_len = smb2_set_info_req_len(__hdr);