Bug 508154 - Multiple ltpchecks failures caused by PRE(sys_fchownat) not handling VKI_AT_FDCWD
Summary: Multiple ltpchecks failures caused by PRE(sys_fchownat) not handling VKI_AT_F...
Status: RESOLVED FIXED
Alias: None
Product: valgrind
Classification: Developer tools
Component: general (other bugs)
Version First Reported In: 3.25 GIT
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: mcermak
URL:
Keywords:
Depends on:
Blocks: 506971
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Reported: 2025-08-12 10:22 UTC by mcermak
Modified: 2025-08-13 12:57 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:

Attachments
proposed patch (2.02 KB, patch)
2025-08-12 10:26 UTC, mcermak 		Details
proposed patch (2.18 KB, patch)
2025-08-13 07:06 UTC, mcermak 		Details
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Description mcermak 2025-08-12 10:22:20 UTC 
I see multiple `make ltpchecks` failures caused by PRE(sys_fchownat) not handling VKI_AT_FDCWD properly.  This specifically impacts aarch64 test results these days.
Comment 1 mcermak 2025-08-12 10:26:12 UTC 
Created attachment 183985 [details]
proposed patch
Comment 2 Mark Wielaard 2025-08-12 17:51:26 UTC 
(In reply to mcermak from comment #1)
> Created attachment 183985 [details]
> proposed patch

> -   if ( !ML_(fd_allowed)(SARG1, "fchownat", tid, False) )
> +   if ( (arg_1 != VKI_AT_FDCWD) && !ML_(fd_allowed)(arg_1, "fchownat", tid, False) )

This doesn't seem to handle the absolute path case:

       If pathname is absolute, then dirfd is ignored.

Maybe something (untested) like:
const HChar* path = (const HChar*)ARG2;
if (ML_(safe_to_deref)(path, 1) && path[0] != '/')
...
Comment 3 mcermak 2025-08-13 07:06:12 UTC 
Created attachment 184028 [details]
proposed patch

Thank you for the review.  Updated patch attached.  Please check.
Comment 4 Mark Wielaard 2025-08-13 12:54:30 UTC 
(In reply to mcermak from comment #3)
> Created attachment 184028 [details]
> proposed patch
> 
> Thank you for the review.  Updated patch attached.  Please check.

Looks good. Pushed as:

commit b306e8ef2771b03aad6440268c1940886d045576
Author: Martin Cermak <mcermak@redhat.com>
Date:   Wed Aug 13 09:03:13 2025 +0200

    PRE(sys_fchownat) not handling VKI_AT_FDCWD
    
    Multiple `make ltpchecks` failures seem tp be caused by
    PRE(sys_fchownat) not handling VKI_AT_FDCWD properly.
    This specifically impacts aarch64 test results these days.
    
    https://bugs.kde.org/show_bug.cgi?id=508154