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Wed, 24 Jun 2026 20:19:38 -0700 (PDT) Received: from localhost.localdomain ([192.197.201.174]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30c7c52c6c2sm3454343eec.10.2026.06.24.20.19.37 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 24 Jun 2026 20:19:38 -0700 (PDT) From: hewei-gikaku To: Konstantin Komarov Cc: ntfs3@lists.linux.dev, linux-fsdevel@vger.kernel.org, Christian Brauner , linux-kernel@vger.kernel.org, HE WEI , stable@vger.kernel.org Subject: [PATCH v2] fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list() Date: Thu, 25 Jun 2026 12:19:30 +0900 Message-ID: <20260625031932.9412-1-skyexpoc@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: HE WEI (ギカク) ni_create_attr_list() allocates a fixed buffer of al_aligned(record_size) (== record_size) bytes and then walks every attribute of the primary MFT record, writing one ATTR_LIST_ENTRY per attribute and advancing the cursor by le_size(name_len), with no check against the end of the buffer; the total size is only computed after the loop. A minimum-size resident attribute occupies SIZEOF_RESIDENT (0x18 = 24) bytes on disk, but an unnamed attribute expands to le_size(0) (0x20 = 32) bytes in the list. Because the number of attributes in a record is not bounded (mi_enum_attr() accepts arbitrarily many equal-type, nameless minimum-size attributes), a crafted record packed with such attributes produces a list larger than record_size and overflows the heap buffer. This is reachable from a crafted, loop-mounted NTFS image: opening the file and adding an attribute (e.g. via setxattr) drives ntfs_set_ea() -> ni_insert_resident() -> ni_insert_attr() -> ni_ins_attr_ext() -> ni_create_attr_list(). BUG: KASAN: slab-out-of-bounds in ni_create_attr_list+0xc48/0x1058 Write of size 4 at addr ffff000008984c00 by task setfattr/345 ni_create_attr_list+0xc48/0x1058 ni_ins_attr_ext+0x510/0x7c0 ni_insert_attr+0x3f8/0x70c ni_insert_resident+0xc8/0x3b0 ntfs_set_ea+0x66c/0xd28 ntfs_setxattr+0x4d8/0x5b0 __arm64_sys_setxattr+0xa4/0x124 Allocated by task 345: ni_create_attr_list+0x188/0x1058 The buggy address belongs to the cache kmalloc-1k of size 1024 (the write lands at object+1024). Size the buffer from the actual attributes instead of assuming a single record_size is always enough. Fixes: 4342306f0f0d ("fs/ntfs3: Add file operations and implementation") Cc: stable@vger.kernel.org Signed-off-by: HE WEI (ギカク) --- v2: - Add Cc: stable@vger.kernel.org: this is an attacker-controlled on-disk image heap out-of-bounds write and should be backported. - No functional change from v1; widening Cc (linux-fsdevel, VFS) for review, as the v1 posting received no response. - Drop a redundant self Reported-by. v1: https://lore.kernel.org/all/20260610002929.51765-1-skyexpoc@gmail.com/ --- fs/ntfs3/frecord.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c index 2e901d073fe9..6488d7a415c0 100644 --- a/fs/ntfs3/frecord.c +++ b/fs/ntfs3/frecord.c @@ -768,10 +768,23 @@ int ni_create_attr_list(struct ntfs_inode *ni) rs = sbi->record_size; /* - * Skip estimating exact memory requirement. - * Looks like one record_size is always enough. + * Compute the exact size of the attribute list. Each attribute in the + * record yields one ATTR_LIST_ENTRY of le_size(name_len) bytes. The + * minimum on-disk attribute is SIZEOF_RESIDENT (0x18) bytes, but an + * unnamed one expands to le_size(0) (0x20) here, so a record crafted + * with many such attributes needs more than a single record_size; the + * previous fixed kzalloc(record_size) could therefore be overflowed by + * an attacker-controlled record. */ - le = kzalloc(al_aligned(rs), GFP_NOFS); + lsize = 0; + attr = NULL; + while ((attr = mi_enum_attr(ni, &ni->mi, attr))) + lsize += le_size(attr->name_len); + + if (!lsize) + return -EINVAL; + + le = kzalloc(al_aligned(lsize), GFP_NOFS); if (!le) return -ENOMEM; @@ -781,7 +794,6 @@ int ni_create_attr_list(struct ntfs_inode *ni) attr = NULL; nb = 0; free_b = 0; - attr = NULL; for (; (attr = mi_enum_attr(ni, &ni->mi, attr)); le = Add2Ptr(le, sz)) { sz = le_size(attr->name_len); -- 2.43.0