Re: [PATCH 1/2] ksmbd: fix negative timestamps being saved to disk

[Ian Bridges <icb@fastmail.org>]

Hi,

On Thu, Nov 12, 2026 at 12:16:36PM +0100, koraynilay wrote:
> When setting a timestamp before epoch 0, ksmbd converts it from NT
> format to Unix format without normalizing it, leading to the nanoseconds
> field to be saved (on-disk too) as a negative number, which leads to a
> garbled stat command output and a reported +4 seconds in the timestamp.

I tested this with the ksmbd code from ksmbd-for-next. Before the
patch, setting an access or write time before 1970 with a fraction of
a second stored the wrong time on disk. The stored time was about four
seconds late, stat showed garbage for the fraction, and a query over
SMB returned the wrong time too. With the patch, the time on disk and
the time returned over SMB match the time that was set. Times after
1970, and whole seconds before it, behave as before. smbtorture gives
the same results as without the patch, and KASAN reports nothing.

Reviewed-by: Ian Bridges <icb@fastmail.org>
Tested-by: Ian Bridges <icb@fastmail.org>