From: Jan Hendrik Farr <kernel@jfarr.cc>
To: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Alan Huang <mmpgouride@gmail.com>,
kees@kernel.org, gustavoars@kernel.org, thorsten.blum@toblux.com,
linux-bcachefs@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] Revert "bcachefs: Annotate struct bch_xattr with __counted_by()"
Date: Thu, 1 May 2025 21:22:26 +0200 [thread overview]
Message-ID: <aBPJ8ueDzztmDOSO@archlinux> (raw)
In-Reply-To: <wsymhks7o6zbsjvac7bmi6vhjkk56ovp2vclrla64sqcquda2x@ikfk7tt76gec>
On 01 15:16:55, Kent Overstreet wrote:
> On Fri, May 02, 2025 at 02:41:50AM +0800, Alan Huang wrote:
> > This reverts commit 86e92eeeb23741a072fe7532db663250ff2e726a.
> >
> > After the x_name, there is a value. According to the disscussion[1],
> > __counted_by assumes that the flexible array member contains exactly
> > the amount of elements that are specified. Now there are users came across
> > buffer overflow caused by the __counted_by here[2], so revert that.
> >
> > [1] https://lore.kernel.org/lkml/Zv8VDKWN1GzLRT-_@archlinux/T/#m0ce9541c5070146320efd4f928cc1ff8de69e9b2
> > [2] https://privatebin.net/?a0d4e97d590d71e1#9bLmp2Kb5NU6X6cZEucchDcu88HzUQwHUah8okKPReEt
> >
> > Signed-off-by: Alan Huang <mmpgouride@gmail.com>
> > ---
> > fs/bcachefs/xattr_format.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/bcachefs/xattr_format.h b/fs/bcachefs/xattr_format.h
> > index c7916011ef34..e9f810539552 100644
> > --- a/fs/bcachefs/xattr_format.h
> > +++ b/fs/bcachefs/xattr_format.h
> > @@ -13,7 +13,7 @@ struct bch_xattr {
> > __u8 x_type;
> > __u8 x_name_len;
> > __le16 x_val_len;
> > - __u8 x_name[] __counted_by(x_name_len);
> > + __u8 x_name[];
>
> this needs a comment, so we don't make the same mistake again
Better yet: change x_name to x_name_and_value
>
> > } __packed __aligned(8);
> >
> > #endif /* _BCACHEFS_XATTR_FORMAT_H */
> > --
> > 2.48.1
> >
prev parent reply other threads:[~2025-05-01 19:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-01 18:41 [PATCH] Revert "bcachefs: Annotate struct bch_xattr with __counted_by()" Alan Huang
2025-05-01 19:09 ` Jan Hendrik Farr
2025-05-01 19:16 ` Kent Overstreet
2025-05-01 19:22 ` Jan Hendrik Farr [this message]
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