| Message ID | 20250325104634.162496-2-mszeredi@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ovl: metacopy/verity fixes and improvements | expand |
On Tue, 2025-03-25 at 11:46 +0100, Miklos Szeredi wrote: > In theory overlayfs could support upper layer directly referring to a > data > layer, but there's no current use case for this. > > Originally, when data-only layers were introduced, this wasn't > allowed, > only introduced by the "datadir+" feature, but without actually > handling > this case, resulting in an Oops. > > Fix by disallowing datadir without lowerdir. > > Reported-by: Giuseppe Scrivano <gscrivan@redhat.com> > Fixes: 24e16e385f22 ("ovl: add support for appending lowerdirs one by > one") > Cc: <stable@vger.kernel.org> # v6.7 > Reviewed-by: Amir Goldstein <amir73il@gmail.com> > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Reviewed-by: Alexander Larsson <alexl@redhat.com> > return ERR_PTR(-EINVAL); > } > > + if (ctx->nr == ctx->nr_data) { > + pr_err("at least one non-data lowerdir is > required\n"); > + return ERR_PTR(-EINVAL); > + } > + > err = -EINVAL; > for (i = 0; i < ctx->nr; i++) { > l = &ctx->lower[i];
On Tue, Mar 25, 2025 at 11:46:29AM +0100, Miklos Szeredi wrote: > In theory overlayfs could support upper layer directly referring to a data > layer, but there's no current use case for this. > > Originally, when data-only layers were introduced, this wasn't allowed, > only introduced by the "datadir+" feature, but without actually handling > this case, resulting in an Oops. > > Fix by disallowing datadir without lowerdir. > > Reported-by: Giuseppe Scrivano <gscrivan@redhat.com> > Fixes: 24e16e385f22 ("ovl: add support for appending lowerdirs one by one") > Cc: <stable@vger.kernel.org> # v6.7 > Reviewed-by: Amir Goldstein <amir73il@gmail.com> > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> > --- Reviewed-by: Christian Brauner <brauner@kernel.org>
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 86ae6f6da36b..b11094acdd8f 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1137,6 +1137,11 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, return ERR_PTR(-EINVAL); } + if (ctx->nr == ctx->nr_data) { + pr_err("at least one non-data lowerdir is required\n"); + return ERR_PTR(-EINVAL); + } + err = -EINVAL; for (i = 0; i < ctx->nr; i++) { l = &ctx->lower[i];
In theory overlayfs could support upper layer directly referring to a data layer, but there's no current use case for this. Originally, when data-only layers were introduced, this wasn't allowed, only introduced by the "datadir+" feature, but without actually handling this case, resulting in an Oops. Fix by disallowing datadir without lowerdir. Reported-by: Giuseppe Scrivano <gscrivan@redhat.com> Fixes: 24e16e385f22 ("ovl: add support for appending lowerdirs one by one") Cc: <stable@vger.kernel.org> # v6.7 Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> --- fs/overlayfs/super.c | 5 +++++ 1 file changed, 5 insertions(+)