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* FAILED: patch "[PATCH] fs/ntfs3: fix slab-out-of-bounds write in" failed to apply to 6.1-stable tree
@ 2026-09-08 10:01 gregkh
  2026-09-10  1:59 ` [PATCH 6.1.y 1/3] fs/ntfs3: Add more checks in mi_enum_attr (part 2) Sasha Levin
  0 siblings, 1 reply; 4+ messages in thread
From: gregkh @ 2026-09-08 10:01 UTC (permalink / raw)
  To: skyexpoc, almaz.alexandrovich; +Cc: stable


The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 7c4841e2a62794a3bab7c1ff0540580f387e377f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090804-handiwork-afford-7887@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7c4841e2a62794a3bab7c1ff0540580f387e377f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?HE=20WEI=EF=BC=88=E3=82=AE=E3=82=AB=E3=82=AF=EF=BC=89?=
 <skyexpoc@gmail.com>
Date: Wed, 10 Jun 2026 09:29:29 +0900
Subject: [PATCH] fs/ntfs3: fix slab-out-of-bounds write in
 ni_create_attr_list()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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")
Reported-by: HE WEI（ギカク） <skyexpoc@gmail.com>
Signed-off-by: HE WEI（ギカク） <skyexpoc@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
index 547c8ab1b6b8..3ad309d38fe8 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);


^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-09-10  1:59 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-09-08 10:01 FAILED: patch "[PATCH] fs/ntfs3: fix slab-out-of-bounds write in" failed to apply to 6.1-stable tree gregkh
2026-09-10  1:59 ` [PATCH 6.1.y 1/3] fs/ntfs3: Add more checks in mi_enum_attr (part 2) Sasha Levin
2026-09-10  1:59   ` [PATCH 6.1.y 2/3] fs/ntfs3: Mark inode as bad as soon as error detected in mi_enum_attr() Sasha Levin
2026-09-10  1:59   ` [PATCH 6.1.y 3/3] fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list() Sasha Levin

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