WARNING in nla_get_range_unsigned

WARNING in nla_get_range_unsigned

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0f091e43 netlabel: remove unused param from audit_log_form..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14865df2900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=61025c6fd3261bb1
dashboard link: https://syzkaller.appspot.com/bug?extid=353df1490da781637624
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12d7b769900000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14e7aa56900000

The issue was bisected to:

commit 8aa26c575fb343ebde810b30dad0cba7d8121efb
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Tue Aug 18 08:17:33 2020 +0000

    netlink: make NLA_BINARY validation more flexible

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=104486c1900000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=124486c1900000
console output: https://syzkaller.appspot.com/x/log.txt?x=144486c1900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+353df1490da781637624@syzkaller.appspotmail.com
Fixes: 8aa26c575fb3 ("netlink: make NLA_BINARY validation more flexible")

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6854 at lib/nlattr.c:117 nla_get_range_unsigned+0x157/0x530 lib/nlattr.c:117
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 6854 Comm: syz-executor416 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:231
 __warn.cold+0x20/0x4a kernel/panic.c:600
 report_bug+0x1bd/0x210 lib/bug.c:198
 handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234
 exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254
 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:nla_get_range_unsigned+0x157/0x530 lib/nlattr.c:117
Code: 2a 03 00 00 44 0f b6 3b 48 c7 c6 40 9f 96 88 4c 89 ff e8 3c 34 c4 fd 41 80 ff 0b 77 11 42 ff 24 fd 60 99 96 88 e8 69 37 c4 fd <0f> 0b eb 8f e8 60 37 c4 fd 0f 0b 5b 41 5c 41 5d 41 5e 41 5f 5d e9
RSP: 0018:ffffc90000f17190 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffff89180640 RCX: ffffffff83b006e8
RDX: ffff8880a79a8300 RSI: ffffffff83b007a7 RDI: 0000000000000003
RBP: ffffc90000f171b8 R08: 0000000000000000 R09: ffff8880972a4370
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000f17278
R13: ffffffff89180641 R14: 0000000000008c60 R15: ffffffff89180640
 netlink_policy_dump_write+0x2ae/0xea0 net/netlink/policy.c:270
 ctrl_dumppolicy+0x4a8/0x900 net/netlink/genetlink.c:1099
 genl_lock_dumpit+0x7f/0xb0 net/netlink/genetlink.c:553
 netlink_dump+0x4cd/0xf60 net/netlink/af_netlink.c:2246
 __netlink_dump_start+0x643/0x900 net/netlink/af_netlink.c:2354
 genl_family_rcv_msg_dumpit+0x2ac/0x310 net/netlink/genetlink.c:616
 genl_family_rcv_msg net/netlink/genetlink.c:711 [inline]
 genl_rcv_msg+0x75f/0x980 net/netlink/genetlink.c:731
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:742
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4402a9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd2f689438 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402a9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ab0
R13: 0000000000401b40 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[PATCH] netlink: policy: correct validation type check

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

In the policy export for binary attributes I erroneously used
a != NLA_VALIDATE_NONE comparison instead of checking for the
two possible values, which meant that if a validation function
pointer ended up aliasing the min/max as negatives, we'd hit
a warning in nla_get_range_unsigned().

Fix this to correctly check for only the two types that should
be handled here, i.e. range with or without warn-too-long.

Reported-by: syzbot+353df1490da781637624@syzkaller.appspotmail.com
Fixes: 8aa26c575fb3 ("netlink: make NLA_BINARY validation more flexible")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/netlink/policy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netlink/policy.c b/net/netlink/policy.c
index 7b1f50531cd3..5c9e7530865f 100644
--- a/net/netlink/policy.c
+++ b/net/netlink/policy.c
@@ -264,7 +264,8 @@ int netlink_policy_dump_write(struct sk_buff *skb, unsigned long _state)
 		else
 			type = NL_ATTR_TYPE_BINARY;
 
-		if (pt->validation_type != NLA_VALIDATE_NONE) {
+		if (pt->validation_type == NLA_VALIDATE_RANGE ||
+		    pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG) {
 			struct netlink_range_validation range;
 
 			nla_get_range_unsigned(pt, &range);
-- 
2.26.2

Re: [PATCH] netlink: policy: correct validation type check

[David Miller]

From: Johannes Berg <johannes@sipsolutions.net>
Date: Mon, 31 Aug 2020 20:28:05 +0200

> From: Johannes Berg <johannes.berg@intel.com>
> 
> In the policy export for binary attributes I erroneously used
> a != NLA_VALIDATE_NONE comparison instead of checking for the
> two possible values, which meant that if a validation function
> pointer ended up aliasing the min/max as negatives, we'd hit
> a warning in nla_get_range_unsigned().
> 
> Fix this to correctly check for only the two types that should
> be handled here, i.e. range with or without warn-too-long.
> 
> Reported-by: syzbot+353df1490da781637624@syzkaller.appspotmail.com
> Fixes: 8aa26c575fb3 ("netlink: make NLA_BINARY validation more flexible")
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Applied, thank you.

Re: WARNING in nla_get_range_unsigned

[Ido Schimmel]

On Sat, Dec 17, 2022 at 05:21:24PM +0800, Wei Chen wrote:
> Dear Linux Developers,
> 
> Recently, when using our tool to fuzz kernel, the following crash was
> triggered. Although this crash has been reported by syzbot
> https://syzkaller.appspot.com/bug?id=32e20c07949c6d6006f26466022469e33ae69108
> and fixed in commit netlink: policy: correct validation type check
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c30a3c957c885e618ddffc065f888be4f8d5a9bd>,
> it still happens in the latest kernel version.
> 
> HEAD commit:  76dcd734eca
> git tree: linux-next
> compiler: clang 12.0.0
> console output:
> https://drive.google.com/file/d/1reeOfFkfJp4-GUz_uMTh-uWXPLBJDcA6/view?usp=share_link
> kernel config:
> https://drive.google.com/file/d/1jH4qV5XblPADvMDUlvS7DwtW0FroMoVB/view?usp=share_link
> syz repro:
> https://drive.google.com/file/d/1Ong8vQn675RFU7R1O5HfiwWxp4UhnaIF/view?usp=share_link

Can be reproduced with:

# tc action add mpls push label 3

Assuming you patch iproute2 to encode a wrong label length. For example:

diff --git a/tc/m_mpls.c b/tc/m_mpls.c
index 9b39d8533c21..2a43ca6c4dd3 100644
--- a/tc/m_mpls.c
+++ b/tc/m_mpls.c
@@ -191,7 +191,7 @@ static int parse_mpls(struct action_util *a, int *argc_p, char ***argv_p,
 	tail = addattr_nest(n, MAX_MSG, tca_id | NLA_F_NESTED);
 	addattr_l(n, MAX_MSG, TCA_MPLS_PARMS, &parm, sizeof(parm));
 	if (label != 0xffffffff)
-		addattr_l(n, MAX_MSG, TCA_MPLS_LABEL, &label, sizeof(label));
+		addattr_l(n, MAX_MSG, TCA_MPLS_LABEL, &label, 8);
 	if (proto)
 		addattr_l(n, MAX_MSG, TCA_MPLS_PROTO, &proto, sizeof(proto));
 	if (tc != 0xff)

It does not seem valid to use NLA_POLICY_VALIDATE_FN() without
NLA_BINARY. Fixed for me by:

diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index ff47ce4d3968..6b26bdb999d7 100644
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -134,6 +134,11 @@ static int valid_label(const struct nlattr *attr,
 {
 	const u32 *label = nla_data(attr);
 
+	if (nla_len(attr) != sizeof(*label)) {
+		NL_SET_ERR_MSG_MOD(extack, "Invalid MPLS label length");
+		return -EINVAL;
+	}
+
 	if (*label & ~MPLS_LABEL_MASK || *label == MPLS_LABEL_IMPLNULL) {
 		NL_SET_ERR_MSG_MOD(extack, "MPLS label out of range");
 		return -EINVAL;
@@ -145,7 +150,8 @@ static int valid_label(const struct nlattr *attr,
 static const struct nla_policy mpls_policy[TCA_MPLS_MAX + 1] = {
 	[TCA_MPLS_PARMS]	= NLA_POLICY_EXACT_LEN(sizeof(struct tc_mpls)),
 	[TCA_MPLS_PROTO]	= { .type = NLA_U16 },
-	[TCA_MPLS_LABEL]	= NLA_POLICY_VALIDATE_FN(NLA_U32, valid_label),
+	[TCA_MPLS_LABEL]	= NLA_POLICY_VALIDATE_FN(NLA_BINARY,
+							 valid_label),
 	[TCA_MPLS_TC]		= NLA_POLICY_RANGE(NLA_U8, 0, 7),
 	[TCA_MPLS_TTL]		= NLA_POLICY_MIN(NLA_U8, 1),
 	[TCA_MPLS_BOS]		= NLA_POLICY_RANGE(NLA_U8, 0, 1),

But please test with your reproducer as well.

For net-next we can try to remove the first argument from
NLA_POLICY_VALIDATE_FN() and set NLA_BINARY which is what everyone is
passing anyway.

Adding Johannes in case he has a better idea.

> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: Wei Chen <harperchen1110@gmail.com>
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 17743 at lib/nlattr.c:118
> nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117
> Modules linked in:
> CPU: 0 PID: 17743 Comm: syz-executor.0 Not tainted 6.1.0-rc8 #3
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
> RIP: 0010:nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117
> Code: 8d ff 49 8b 75 08 ba 10 00 00 00 4c 89 f7 e8 0f d8 f8 02 5b 41 5c 41
> 5d 41 5e 41 5f 5d c3 e8 0f 57 7a ff eb 05 e8 08 57 7a ff <0f> 0b e9 a9 fe
> ff ff 90 55 41 57 41 56 41 54 53 49 89 f6 49 89 fc
> RSP: 0018:ffffc90002df39b8 EFLAGS: 00010287
> RAX: ffffffff81ad2f51 RBX: ffffffff85364d28 RCX: 0000000000040000
> RDX: ffffc90000add000 RSI: 0000000000000268 RDI: 0000000000000269
> RBP: 000000000000f940 R08: ffffffff81ad2dd8 R09: 0000000000000000
> R10: 0001ffffffffffff R11: ffff888045136780 R12: ffff88803e174000
> R13: ffffffff85364d20 R14: ffffc90002df3a30 R15: ffffffff85364d21
> FS:  00007fab1e5c8700(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000073f8d0 CR3: 000000004a789000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
>  <TASK>
>  __netlink_policy_dump_write_attr+0x23d/0x990 net/netlink/policy.c:310
>  netlink_policy_dump_write_attr+0x22/0x30 net/netlink/policy.c:411
>  netlink_ack_tlv_fill net/netlink/af_netlink.c:2454 [inline]
>  netlink_ack+0x546/0x760 net/netlink/af_netlink.c:2506
>  netlink_rcv_skb+0x1b7/0x240 net/netlink/af_netlink.c:2546
>  rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6109
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x5e9/0x6b0 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x739/0x860 net/netlink/af_netlink.c:1921
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg net/socket.c:734 [inline]
>  ____sys_sendmsg+0x38f/0x500 net/socket.c:2482
>  ___sys_sendmsg net/socket.c:2536 [inline]
>  __sys_sendmsg+0x197/0x230 net/socket.c:2565
>  __do_sys_sendmsg net/socket.c:2574 [inline]
>  __se_sys_sendmsg net/socket.c:2572 [inline]
>  __x64_sys_sendmsg+0x42/0x50 net/socket.c:2572
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x4697f9
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fab1e5c7c48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9
> RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
> RBP: 00000000004d29e9 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000077bf80
> R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffd7c0e6920
>  </TASK>
> ---[ end trace 0000000000000000 ]---
> 
> Best,
> Wei
> 
> -- 
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WARNING in nla_get_range_unsigned

[Wei Chen]

Dear Linux Developers,

Recently, when using our tool to fuzz kernel, the following crash was
triggered. Although this crash has been reported by syzbot
https://syzkaller.appspot.com/bug?id=32e20c07949c6d6006f26466022469e33ae69108
and fixed in commit netlink: policy: correct validation type check
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c30a3c957c885e618ddffc065f888be4f8d5a9bd,
it still happens in the latest kernel version.

HEAD commit:  76dcd734eca
git tree: linux-next
compiler: clang 12.0.0
console output:
https://drive.google.com/file/d/1reeOfFkfJp4-GUz_uMTh-uWXPLBJDcA6/view?usp=share_link
kernel config: https://drive.google.com/file/d/1jH4qV5XblPADvMDUlvS7DwtW0FroMoVB/view?usp=share_link
syz repro: https://drive.google.com/file/d/1Ong8vQn675RFU7R1O5HfiwWxp4UhnaIF/view?usp=share_link

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: Wei Chen <harperchen1110@gmail.com>

------------[ cut here ]------------
WARNING: CPU: 0 PID: 17743 at lib/nlattr.c:118
nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117
Modules linked in:
CPU: 0 PID: 17743 Comm: syz-executor.0 Not tainted 6.1.0-rc8 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
RIP: 0010:nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117
Code: 8d ff 49 8b 75 08 ba 10 00 00 00 4c 89 f7 e8 0f d8 f8 02 5b 41
5c 41 5d 41 5e 41 5f 5d c3 e8 0f 57 7a ff eb 05 e8 08 57 7a ff <0f> 0b
e9 a9 fe ff ff 90 55 41 57 41 56 41 54 53 49 89 f6 49 89 fc
RSP: 0018:ffffc90002df39b8 EFLAGS: 00010287
RAX: ffffffff81ad2f51 RBX: ffffffff85364d28 RCX: 0000000000040000
RDX: ffffc90000add000 RSI: 0000000000000268 RDI: 0000000000000269
RBP: 000000000000f940 R08: ffffffff81ad2dd8 R09: 0000000000000000
R10: 0001ffffffffffff R11: ffff888045136780 R12: ffff88803e174000
R13: ffffffff85364d20 R14: ffffc90002df3a30 R15: ffffffff85364d21
FS:  00007fab1e5c8700(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000073f8d0 CR3: 000000004a789000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 __netlink_policy_dump_write_attr+0x23d/0x990 net/netlink/policy.c:310
 netlink_policy_dump_write_attr+0x22/0x30 net/netlink/policy.c:411
 netlink_ack_tlv_fill net/netlink/af_netlink.c:2454 [inline]
 netlink_ack+0x546/0x760 net/netlink/af_netlink.c:2506
 netlink_rcv_skb+0x1b7/0x240 net/netlink/af_netlink.c:2546
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6109
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x5e9/0x6b0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x739/0x860 net/netlink/af_netlink.c:1921
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 ____sys_sendmsg+0x38f/0x500 net/socket.c:2482
 ___sys_sendmsg net/socket.c:2536 [inline]
 __sys_sendmsg+0x197/0x230 net/socket.c:2565
 __do_sys_sendmsg net/socket.c:2574 [inline]
 __se_sys_sendmsg net/socket.c:2572 [inline]
 __x64_sys_sendmsg+0x42/0x50 net/socket.c:2572
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x4697f9
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fab1e5c7c48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000004d29e9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000077bf80
R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffd7c0e6920
 </TASK>
---[ end trace 0000000000000000 ]---

Best,
Wei