Coverity: z_erofs_handle_inplace_io(): Uninitialized variables

Coverity: z_erofs_handle_inplace_io(): Uninitialized variables

[coverity-bot]

Hello!

This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20210408 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:

  Wed Apr 7 13:17:55 2021 +0800
    c660a3a86e7e ("erofs: support decompress big pcluster for lz4 backend")

Coverity reported the following:

*** CID 1503704:  Uninitialized variables  (UNINIT)
/fs/erofs/decompressor.c: 160 in z_erofs_handle_inplace_io()
154     	}
155     	kunmap_atomic(inpage);
156     	might_sleep();
157     	while (1) {
158     		src = vm_map_ram(rq->in, nrpages_in, -1);
159     		/* retry two more times (totally 3 times) */
vvv     CID 1503704:  Uninitialized variables  (UNINIT)
vvv     Using uninitialized value "i".
160     		if (src || ++i >= 3)
161     			break;
162     		vm_unmap_aliases();
163     	}
164     	*maptype = 1;
165     	return src;

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1503704 ("Uninitialized variables")
Fixes: c660a3a86e7e ("erofs: support decompress big pcluster for lz4 backend")

Thanks for your attention!

-- 
Coverity-bot

Re: Coverity: z_erofs_handle_inplace_io(): Uninitialized variables

[Gao Xiang]

Hi,

On Thu, Apr 08, 2021 at 05:09:14PM -0700, coverity-bot wrote:
> Hello!
> 
> This is an experimental semi-automated report about issues detected by
> Coverity from a scan of next-20210408 as part of the linux-next scan project:
> https://scan.coverity.com/projects/linux-next-weekly-scan
> 
> You're getting this email because you were associated with the identified
> lines of code (noted below) that were touched by commits:
> 
>   Wed Apr 7 13:17:55 2021 +0800
>     c660a3a86e7e ("erofs: support decompress big pcluster for lz4 backend")
> 
> Coverity reported the following:
> 
> *** CID 1503704:  Uninitialized variables  (UNINIT)
> /fs/erofs/decompressor.c: 160 in z_erofs_handle_inplace_io()
> 154     	}
> 155     	kunmap_atomic(inpage);
> 156     	might_sleep();
> 157     	while (1) {
> 158     		src = vm_map_ram(rq->in, nrpages_in, -1);
> 159     		/* retry two more times (totally 3 times) */
> vvv     CID 1503704:  Uninitialized variables  (UNINIT)
> vvv     Using uninitialized value "i".
> 160     		if (src || ++i >= 3)
> 161     			break;
> 162     		vm_unmap_aliases();
> 163     	}
> 164     	*maptype = 1;
> 165     	return src;

Thanks for the report!

This bug was reported by Colin King before (next-20210407), and has already
been fixed in (next-20210408), see:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/fs/erofs/decompressor.c?h=next-20210408#n157
and
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/fs/erofs/internal.h?h=next-20210408#n405

Thanks,
Gao Xiang

> 
> If this is a false positive, please let us know so we can mark it as
> such, or teach the Coverity rules to be smarter. If not, please make
> sure fixes get into linux-next. :) For patches fixing this, please
> include these lines (but double-check the "Fixes" first):
> 
> Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
> Addresses-Coverity-ID: 1503704 ("Uninitialized variables")
> Fixes: c660a3a86e7e ("erofs: support decompress big pcluster for lz4 backend")
> 
> Thanks for your attention!
> 
> -- 
> Coverity-bot
> 

Re: Coverity: z_erofs_handle_inplace_io(): Uninitialized variables

[Kees Cook]

On Fri, Apr 09, 2021 at 09:01:46AM +0800, Gao Xiang wrote:
> Hi,
> 
> On Thu, Apr 08, 2021 at 05:09:14PM -0700, coverity-bot wrote:
> > Hello!
> > 
> > This is an experimental semi-automated report about issues detected by
> > Coverity from a scan of next-20210408 as part of the linux-next scan project:
> > https://scan.coverity.com/projects/linux-next-weekly-scan
> > 
> > You're getting this email because you were associated with the identified
> > lines of code (noted below) that were touched by commits:
> > 
> >   Wed Apr 7 13:17:55 2021 +0800
> >     c660a3a86e7e ("erofs: support decompress big pcluster for lz4 backend")
> > 
> > Coverity reported the following:
> > 
> > *** CID 1503704:  Uninitialized variables  (UNINIT)
> > /fs/erofs/decompressor.c: 160 in z_erofs_handle_inplace_io()
> > 154     	}
> > 155     	kunmap_atomic(inpage);
> > 156     	might_sleep();
> > 157     	while (1) {
> > 158     		src = vm_map_ram(rq->in, nrpages_in, -1);
> > 159     		/* retry two more times (totally 3 times) */
> > vvv     CID 1503704:  Uninitialized variables  (UNINIT)
> > vvv     Using uninitialized value "i".
> > 160     		if (src || ++i >= 3)
> > 161     			break;
> > 162     		vm_unmap_aliases();
> > 163     	}
> > 164     	*maptype = 1;
> > 165     	return src;
> 
> Thanks for the report!
> 
> This bug was reported by Colin King before (next-20210407), and has already
> been fixed in (next-20210408), see:
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/fs/erofs/decompressor.c?h=next-20210408#n157
> and
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/fs/erofs/internal.h?h=next-20210408#n405

Ah-ha, thank you! Colin is fast. :)

-- 
Kees Cook