On Sun, Dec 29, 2024 at 01:58:19PM +0100, Andrey Albershteyn wrote:
> On 2024-12-18 16:35:21, Darrick J. Wong wrote:
> > On Tue, Dec 17, 2024 at 11:58:12PM +0100, Mirsad Todorovac wrote:
> > > The source static analysis tool gave the following advice:
> > >
> > > ./fs/xfs/libxfs/xfs_dir2.c:382:15-22: WARNING opportunity for kmemdup
> > >
> > > → 382 args->value = kmalloc(len,
> > > 383 GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
> > > 384 if (!args->value)
> > > 385 return -ENOMEM;
> > > 386
> > > → 387 memcpy(args->value, name, len);
> > > 388 args->valuelen = len;
> > > 389 return -EEXIST;
> > >
> > > Replacing kmalloc() + memcpy() with kmemdump() doesn't change semantics.
> > > Original code works without fault, so this is not a bug fix but proposed improvement.
> >
> > I guess this is all right, but seeing as this code is shared with
> > userspace ("libxfs"), making this change will just add to the wrappers
> > that we have to have:
> >
> > void *kmemdup_noprof(const void *src, size_t len, gfp_t gfp)
> > {
> > void *p;
> >
> > p = kmalloc_node_track_caller_noprof(len, gfp, NUMA_NO_NODE, _RET_IP_);
> > if (p)
> > memcpy(p, src, len);
> > return p;
> > }
> >
> > Is this sufficiently better? That's a question for the kernel
> > maintainer (cem) and the userspace maintainer (andrey, now cc'd).
> >
> > --D
>
> There's still possibility to set wrong length in args->valuelen,
> which I suppose what this change tries to prevent.
>
> But otherwise wrapper looks good to me
Ok, proceed then.
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> >
> > > Link: https://lwn.net/Articles/198928/
> > > Fixes: 94a69db2367ef ("xfs: use __GFP_NOLOCKDEP instead of GFP_NOFS")
> > > Fixes: 384f3ced07efd ("[XFS] Return case-insensitive match for dentry cache")
> > > Fixes: 2451337dd0439 ("xfs: global error sign conversion")
> > > Cc: Carlos Maiolino <cem@xxxxxxxxxx>
> > > Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
> > > Cc: Chandan Babu R <chandanbabu@xxxxxxxxxx>
> > > Cc: Dave Chinner <dchinner@xxxxxxxxxx>
> > > Cc: linux-xfs@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Signed-off-by: Mirsad Todorovac <mtodorovac69@xxxxxxxxx>
> > > ---
> > > v1:
> > > initial version.
> > >
> > > fs/xfs/libxfs/xfs_dir2.c | 3 +--
> > > 1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
> > > index 202468223bf9..24251e42bdeb 100644
> > > --- a/fs/xfs/libxfs/xfs_dir2.c
> > > +++ b/fs/xfs/libxfs/xfs_dir2.c
> > > @@ -379,12 +379,11 @@ xfs_dir_cilookup_result(
> > > !(args->op_flags & XFS_DA_OP_CILOOKUP))
> > > return -EEXIST;
> > >
> > > - args->value = kmalloc(len,
> > > + args->value = kmemdup(name, len,
> > > GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
> > > if (!args->value)
> > > return -ENOMEM;
> > >
> > > - memcpy(args->value, name, len);
> > > args->valuelen = len;
> > > return -EEXIST;
> > > }
> > > --
> > > 2.43.0
> > >
> > >
> >
>
> --
> - Andrey
>
>
