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([2001:41d0:303:db6b::]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a820c8556sm121627405e9.4.2026.05.01.04.02.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 May 2026 04:02:19 -0700 (PDT) From: Tristan Madani To: Viacheslav Dubeyko , John Paul Adrian Glaubitz , Yangtao Li Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Tristan Madani , syzbot+217eb327242d08197efb@syzkaller.appspotmail.com Subject: [PATCH 2/3] hfs/hfsplus: initialize data buffer in hfs_bnode_read_u16 and hfs_bnode_read_u8 Date: Fri, 1 May 2026 11:02:16 +0000 Message-ID: <20260501110218.29906-2-tristmd@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260501110218.29906-1-tristmd@gmail.com> References: <20260501110218.29906-1-tristmd@gmail.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tristan Madani hfs_bnode_read_u16() and hfs_bnode_read_u8() declare local data buffers without initialization, then pass them to hfs_bnode_read(). If is_bnode_offset_valid() fails inside hfs_bnode_read(), the function returns early without writing to the buffer, leaving it uninitialized. The caller then returns the garbage value to its caller. This triggers KMSAN uninit-value reports when a corrupted HFS+ image has a node_size of 1, causing rec_off to underflow in hfs_bnode_find() and the subsequent hfs_bnode_read_u16() to operate on an invalid offset. Zero-initialize both buffers so that callers get a deterministic zero value when the underlying read fails. Reported-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=217eb327242d08197efb Tested-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com Fixes: a431930c9bac ("hfs: fix slab-out-of-bounds in hfs_bnode_read()") Cc: stable@vger.kernel.org Signed-off-by: Tristan Madani --- fs/hfs/bnode.c | 4 ++-- fs/hfsplus/bnode.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/hfs/bnode.c b/fs/hfs/bnode.c index c00645a4a5733..08307faea7a68 100644 --- a/fs/hfs/bnode.c +++ b/fs/hfs/bnode.c @@ -97,7 +97,7 @@ void hfs_bnode_read(struct hfs_bnode *node, void *buf, u32 off, u32 len) u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 off) { - __be16 data; + __be16 data = 0; // optimize later... hfs_bnode_read(node, &data, off, 2); return be16_to_cpu(data); @@ -105,7 +105,7 @@ u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 off) u8 hfs_bnode_read_u8(struct hfs_bnode *node, u32 off) { - u8 data; + u8 data = 0; // optimize later... hfs_bnode_read(node, &data, off, 1); return data; diff --git a/fs/hfsplus/bnode.c b/fs/hfsplus/bnode.c index f8b5a8ae58ff5..35790085b5b2e 100644 --- a/fs/hfsplus/bnode.c +++ b/fs/hfsplus/bnode.c @@ -55,7 +55,7 @@ void hfs_bnode_read(struct hfs_bnode *node, void *buf, u32 off, u32 len) u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 off) { - __be16 data; + __be16 data = 0; /* TODO: optimize later... */ hfs_bnode_read(node, &data, off, 2); return be16_to_cpu(data); @@ -63,7 +63,7 @@ u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 off) u8 hfs_bnode_read_u8(struct hfs_bnode *node, u32 off) { - u8 data; + u8 data = 0; /* TODO: optimize later... */ hfs_bnode_read(node, &data, off, 1); return data; -- 2.47.3