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[87.97.53.119]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3997f9a50c1sm13572203f8f.38.2025.03.25.03.46.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Mar 2025 03:46:36 -0700 (PDT) From: Miklos Szeredi To: linux-unionfs@vger.kernel.org Cc: Amir Goldstein , linux-fsdevel@vger.kernel.org, Giuseppe Scrivano , Alexander Larsson , stable@vger.kernel.org Subject: [PATCH v2 1/5] ovl: don't allow datadir only Date: Tue, 25 Mar 2025 11:46:29 +0100 Message-ID: <20250325104634.162496-2-mszeredi@redhat.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250325104634.162496-1-mszeredi@redhat.com> References: <20250325104634.162496-1-mszeredi@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 Fixes: 24e16e385f22 ("ovl: add support for appending lowerdirs one by one") Cc: # v6.7 Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi Reviewed-by: Alexander Larsson Reviewed-by: Christian Brauner --- fs/overlayfs/super.c | 5 +++++ 1 file changed, 5 insertions(+) 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];