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smb: client: fix overflow in passthrough ioctl bounds check

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smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload
before copying it to userspace.

The payload offset and length both come from 32-bit fields. The bounds
check currently adds OutputOffset and qi.input_buffer_length directly, so
the addition can wrap in 32-bit arithmetic before the result is compared
against the response buffer length.

A malicious server can use a large OutputOffset and a small OutputCount
to make the wrapped sum pass the bounds check. The later copy_to_user()
then reads from io_rsp + OutputOffset, outside the response buffer.

Use size_add() for the offset plus length check so overflow is treated as
out of bounds.

Fixes: 2b1116bbe8 ("CIFS: Use common error handling code in smb2_ioctl_query_info()")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Guangshuo Li 2026-07-08 20:35:20 +08:00 committed by Steve French
parent 75f5c412fa
commit a4f27ad055
1 changed files with 2 additions and 2 deletions
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4
fs/smb/client/smb2ops.c
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@ -1772,8 +1772,8 @@ smb2_ioctl_query_info(const unsigned int xid,
if (le32_to_cpu(io_rsp->OutputCount) < qi.input_buffer_length)
qi.input_buffer_length = le32_to_cpu(io_rsp->OutputCount);
if (qi.input_buffer_length > 0 &&
le32_to_cpu(io_rsp->OutputOffset) + qi.input_buffer_length
> rsp_iov[1].iov_len) {
size_add(le32_to_cpu(io_rsp->OutputOffset),
qi.input_buffer_length) > rsp_iov[1].iov_len) {
rc = -EFAULT;
goto out;
}