diff mbox series

[bpf,1/2] xsk: fix OOB map writes when deleting elements

Message ID 20241115125348.654145-2-maciej.fijalkowski@intel.com (mailing list archive)
State New
Delegated to: BPF
Headers show
Series bpf: fix OOB accesses in map_delete_elem callbacks | expand

Checks

Context Check Description
bpf/vmtest-bpf-PR success PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 7 maintainers not CCed: kuba@kernel.org horms@kernel.org pabeni@redhat.com edumazet@google.com john.fastabend@gmail.com hawk@kernel.org jonathan.lemon@gmail.com
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
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Commit Message

Maciej Fijalkowski Nov. 15, 2024, 12:53 p.m. UTC 
Jordy says:

"
In the xsk_map_delete_elem function an unsigned integer
(map->max_entries) is compared with a user-controlled signed integer
(k). Due to implicit type conversion, a large unsigned value for
map->max_entries can bypass the intended bounds check:

	if (k >= map->max_entries)
		return -EINVAL;

This allows k to hold a negative value (between -2147483648 and -2),
which is then used as an array index in m->xsk_map[k], which results
in an out-of-bounds access.

	spin_lock_bh(&m->lock);
	map_entry = &m->xsk_map[k]; // Out-of-bounds map_entry
	old_xs = unrcu_pointer(xchg(map_entry, NULL));  // Oob write
	if (old_xs)
		xsk_map_sock_delete(old_xs, map_entry);
	spin_unlock_bh(&m->lock);

The xchg operation can then be used to cause an out-of-bounds write.
Moreover, the invalid map_entry passed to xsk_map_sock_delete can lead
to further memory corruption.
"

It indeed results in following splat:

[76612.897343] BUG: unable to handle page fault for address: ffffc8fc2e461108
[76612.904330] #PF: supervisor write access in kernel mode
[76612.909639] #PF: error_code(0x0002) - not-present page
[76612.914855] PGD 0 P4D 0
[76612.917431] Oops: Oops: 0002 [#1] PREEMPT SMP
[76612.921859] CPU: 11 UID: 0 PID: 10318 Comm: a.out Not tainted 6.12.0-rc1+ #470
[76612.929189] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
[76612.939781] RIP: 0010:xsk_map_delete_elem+0x2d/0x60
[76612.944738] Code: 00 00 41 54 55 53 48 63 2e 3b 6f 24 73 38 4c 8d a7 f8 00 00 00 48 89 fb 4c 89 e7 e8 2d bf 05 00 48 8d b4 eb 00 01 00 00 31 ff <48> 87 3e 48 85 ff 74 05 e8 16 ff ff ff 4c 89 e7 e8 3e bc 05 00 31
[76612.963774] RSP: 0018:ffffc9002e407df8 EFLAGS: 00010246
[76612.969079] RAX: 0000000000000000 RBX: ffffc9002e461000 RCX: 0000000000000000
[76612.976323] RDX: 0000000000000001 RSI: ffffc8fc2e461108 RDI: 0000000000000000
[76612.983569] RBP: ffffffff80000001 R08: 0000000000000000 R09: 0000000000000007
[76612.990812] R10: ffffc9002e407e18 R11: ffff888108a38858 R12: ffffc9002e4610f8
[76612.998060] R13: ffff888108a38858 R14: 00007ffd1ae0ac78 R15: ffffc9002e4610c0
[76613.005303] FS:  00007f80b6f59740(0000) GS:ffff8897e0ec0000(0000) knlGS:0000000000000000
[76613.013517] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[76613.019349] CR2: ffffc8fc2e461108 CR3: 000000011e3ef001 CR4: 00000000007726f0
[76613.026595] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[76613.033841] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[76613.041086] PKRU: 55555554
[76613.043842] Call Trace:
[76613.046331]  <TASK>
[76613.048468]  ? __die+0x20/0x60
[76613.051581]  ? page_fault_oops+0x15a/0x450
[76613.055747]  ? search_extable+0x22/0x30
[76613.059649]  ? search_bpf_extables+0x5f/0x80
[76613.063988]  ? exc_page_fault+0xa9/0x140
[76613.067975]  ? asm_exc_page_fault+0x22/0x30
[76613.072229]  ? xsk_map_delete_elem+0x2d/0x60
[76613.076573]  ? xsk_map_delete_elem+0x23/0x60
[76613.080914]  __sys_bpf+0x19b7/0x23c0
[76613.084555]  __x64_sys_bpf+0x1a/0x20
[76613.088194]  do_syscall_64+0x37/0xb0
[76613.091832]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
[76613.096962] RIP: 0033:0x7f80b6d1e88d
[76613.100592] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 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 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48
[76613.119631] RSP: 002b:00007ffd1ae0ac68 EFLAGS: 00000206 ORIG_RAX: 0000000000000141
[76613.131330] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f80b6d1e88d
[76613.142632] RDX: 0000000000000098 RSI: 00007ffd1ae0ad20 RDI: 0000000000000003
[76613.153967] RBP: 00007ffd1ae0adc0 R08: 0000000000000000 R09: 0000000000000000
[76613.166030] R10: 00007f80b6f77040 R11: 0000000000000206 R12: 00007ffd1ae0aed8
[76613.177130] R13: 000055ddf42ce1e9 R14: 000055ddf42d0d98 R15: 00007f80b6fab040
[76613.188129]  </TASK>

Fix this by simply changing key type from int to u32.

Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP")
Reported-by: Jordy Zomer <jordyzomer@google.com>
Suggested-by: Jordy Zomer <jordyzomer@google.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
---
 net/xdp/xskmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Greg Kroah-Hartman Nov. 15, 2024, 1:12 p.m. UTC | #1 
On Fri, Nov 15, 2024 at 01:53:47PM +0100, Maciej Fijalkowski wrote:
> Jordy says:
> 
> "
> In the xsk_map_delete_elem function an unsigned integer
> (map->max_entries) is compared with a user-controlled signed integer
> (k). Due to implicit type conversion, a large unsigned value for
> map->max_entries can bypass the intended bounds check:
> 
> 	if (k >= map->max_entries)
> 		return -EINVAL;
> 
> This allows k to hold a negative value (between -2147483648 and -2),
> which is then used as an array index in m->xsk_map[k], which results
> in an out-of-bounds access.
> 
> 	spin_lock_bh(&m->lock);
> 	map_entry = &m->xsk_map[k]; // Out-of-bounds map_entry
> 	old_xs = unrcu_pointer(xchg(map_entry, NULL));  // Oob write
> 	if (old_xs)
> 		xsk_map_sock_delete(old_xs, map_entry);
> 	spin_unlock_bh(&m->lock);
> 
> The xchg operation can then be used to cause an out-of-bounds write.
> Moreover, the invalid map_entry passed to xsk_map_sock_delete can lead
> to further memory corruption.
> "
> 
> It indeed results in following splat:
> 
> [76612.897343] BUG: unable to handle page fault for address: ffffc8fc2e461108
> [76612.904330] #PF: supervisor write access in kernel mode
> [76612.909639] #PF: error_code(0x0002) - not-present page
> [76612.914855] PGD 0 P4D 0
> [76612.917431] Oops: Oops: 0002 [#1] PREEMPT SMP
> [76612.921859] CPU: 11 UID: 0 PID: 10318 Comm: a.out Not tainted 6.12.0-rc1+ #470
> [76612.929189] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
> [76612.939781] RIP: 0010:xsk_map_delete_elem+0x2d/0x60
> [76612.944738] Code: 00 00 41 54 55 53 48 63 2e 3b 6f 24 73 38 4c 8d a7 f8 00 00 00 48 89 fb 4c 89 e7 e8 2d bf 05 00 48 8d b4 eb 00 01 00 00 31 ff <48> 87 3e 48 85 ff 74 05 e8 16 ff ff ff 4c 89 e7 e8 3e bc 05 00 31
> [76612.963774] RSP: 0018:ffffc9002e407df8 EFLAGS: 00010246
> [76612.969079] RAX: 0000000000000000 RBX: ffffc9002e461000 RCX: 0000000000000000
> [76612.976323] RDX: 0000000000000001 RSI: ffffc8fc2e461108 RDI: 0000000000000000
> [76612.983569] RBP: ffffffff80000001 R08: 0000000000000000 R09: 0000000000000007
> [76612.990812] R10: ffffc9002e407e18 R11: ffff888108a38858 R12: ffffc9002e4610f8
> [76612.998060] R13: ffff888108a38858 R14: 00007ffd1ae0ac78 R15: ffffc9002e4610c0
> [76613.005303] FS:  00007f80b6f59740(0000) GS:ffff8897e0ec0000(0000) knlGS:0000000000000000
> [76613.013517] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [76613.019349] CR2: ffffc8fc2e461108 CR3: 000000011e3ef001 CR4: 00000000007726f0
> [76613.026595] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [76613.033841] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [76613.041086] PKRU: 55555554
> [76613.043842] Call Trace:
> [76613.046331]  <TASK>
> [76613.048468]  ? __die+0x20/0x60
> [76613.051581]  ? page_fault_oops+0x15a/0x450
> [76613.055747]  ? search_extable+0x22/0x30
> [76613.059649]  ? search_bpf_extables+0x5f/0x80
> [76613.063988]  ? exc_page_fault+0xa9/0x140
> [76613.067975]  ? asm_exc_page_fault+0x22/0x30
> [76613.072229]  ? xsk_map_delete_elem+0x2d/0x60
> [76613.076573]  ? xsk_map_delete_elem+0x23/0x60
> [76613.080914]  __sys_bpf+0x19b7/0x23c0
> [76613.084555]  __x64_sys_bpf+0x1a/0x20
> [76613.088194]  do_syscall_64+0x37/0xb0
> [76613.091832]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
> [76613.096962] RIP: 0033:0x7f80b6d1e88d
> [76613.100592] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 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 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48
> [76613.119631] RSP: 002b:00007ffd1ae0ac68 EFLAGS: 00000206 ORIG_RAX: 0000000000000141
> [76613.131330] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f80b6d1e88d
> [76613.142632] RDX: 0000000000000098 RSI: 00007ffd1ae0ad20 RDI: 0000000000000003
> [76613.153967] RBP: 00007ffd1ae0adc0 R08: 0000000000000000 R09: 0000000000000000
> [76613.166030] R10: 00007f80b6f77040 R11: 0000000000000206 R12: 00007ffd1ae0aed8
> [76613.177130] R13: 000055ddf42ce1e9 R14: 000055ddf42d0d98 R15: 00007f80b6fab040
> [76613.188129]  </TASK>
> 
> Fix this by simply changing key type from int to u32.
> 
> Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP")
> Reported-by: Jordy Zomer <jordyzomer@google.com>
> Suggested-by: Jordy Zomer <jordyzomer@google.com>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> ---
>  net/xdp/xskmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot
Toke Høiland-Jørgensen Nov. 15, 2024, 3:01 p.m. UTC | #2 
Maciej Fijalkowski <maciej.fijalkowski@intel.com> writes:

> Jordy says:
>
> "
> In the xsk_map_delete_elem function an unsigned integer
> (map->max_entries) is compared with a user-controlled signed integer
> (k). Due to implicit type conversion, a large unsigned value for
> map->max_entries can bypass the intended bounds check:
>
> 	if (k >= map->max_entries)
> 		return -EINVAL;
>
> This allows k to hold a negative value (between -2147483648 and -2),
> which is then used as an array index in m->xsk_map[k], which results
> in an out-of-bounds access.
>
> 	spin_lock_bh(&m->lock);
> 	map_entry = &m->xsk_map[k]; // Out-of-bounds map_entry
> 	old_xs = unrcu_pointer(xchg(map_entry, NULL));  // Oob write
> 	if (old_xs)
> 		xsk_map_sock_delete(old_xs, map_entry);
> 	spin_unlock_bh(&m->lock);
>
> The xchg operation can then be used to cause an out-of-bounds write.
> Moreover, the invalid map_entry passed to xsk_map_sock_delete can lead
> to further memory corruption.
> "
>
> It indeed results in following splat:
>
> [76612.897343] BUG: unable to handle page fault for address: ffffc8fc2e461108
> [76612.904330] #PF: supervisor write access in kernel mode
> [76612.909639] #PF: error_code(0x0002) - not-present page
> [76612.914855] PGD 0 P4D 0
> [76612.917431] Oops: Oops: 0002 [#1] PREEMPT SMP
> [76612.921859] CPU: 11 UID: 0 PID: 10318 Comm: a.out Not tainted 6.12.0-rc1+ #470
> [76612.929189] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019
> [76612.939781] RIP: 0010:xsk_map_delete_elem+0x2d/0x60
> [76612.944738] Code: 00 00 41 54 55 53 48 63 2e 3b 6f 24 73 38 4c 8d a7 f8 00 00 00 48 89 fb 4c 89 e7 e8 2d bf 05 00 48 8d b4 eb 00 01 00 00 31 ff <48> 87 3e 48 85 ff 74 05 e8 16 ff ff ff 4c 89 e7 e8 3e bc 05 00 31
> [76612.963774] RSP: 0018:ffffc9002e407df8 EFLAGS: 00010246
> [76612.969079] RAX: 0000000000000000 RBX: ffffc9002e461000 RCX: 0000000000000000
> [76612.976323] RDX: 0000000000000001 RSI: ffffc8fc2e461108 RDI: 0000000000000000
> [76612.983569] RBP: ffffffff80000001 R08: 0000000000000000 R09: 0000000000000007
> [76612.990812] R10: ffffc9002e407e18 R11: ffff888108a38858 R12: ffffc9002e4610f8
> [76612.998060] R13: ffff888108a38858 R14: 00007ffd1ae0ac78 R15: ffffc9002e4610c0
> [76613.005303] FS:  00007f80b6f59740(0000) GS:ffff8897e0ec0000(0000) knlGS:0000000000000000
> [76613.013517] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [76613.019349] CR2: ffffc8fc2e461108 CR3: 000000011e3ef001 CR4: 00000000007726f0
> [76613.026595] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [76613.033841] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [76613.041086] PKRU: 55555554
> [76613.043842] Call Trace:
> [76613.046331]  <TASK>
> [76613.048468]  ? __die+0x20/0x60
> [76613.051581]  ? page_fault_oops+0x15a/0x450
> [76613.055747]  ? search_extable+0x22/0x30
> [76613.059649]  ? search_bpf_extables+0x5f/0x80
> [76613.063988]  ? exc_page_fault+0xa9/0x140
> [76613.067975]  ? asm_exc_page_fault+0x22/0x30
> [76613.072229]  ? xsk_map_delete_elem+0x2d/0x60
> [76613.076573]  ? xsk_map_delete_elem+0x23/0x60
> [76613.080914]  __sys_bpf+0x19b7/0x23c0
> [76613.084555]  __x64_sys_bpf+0x1a/0x20
> [76613.088194]  do_syscall_64+0x37/0xb0
> [76613.091832]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
> [76613.096962] RIP: 0033:0x7f80b6d1e88d
> [76613.100592] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 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 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48
> [76613.119631] RSP: 002b:00007ffd1ae0ac68 EFLAGS: 00000206 ORIG_RAX: 0000000000000141
> [76613.131330] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f80b6d1e88d
> [76613.142632] RDX: 0000000000000098 RSI: 00007ffd1ae0ad20 RDI: 0000000000000003
> [76613.153967] RBP: 00007ffd1ae0adc0 R08: 0000000000000000 R09: 0000000000000000
> [76613.166030] R10: 00007f80b6f77040 R11: 0000000000000206 R12: 00007ffd1ae0aed8
> [76613.177130] R13: 000055ddf42ce1e9 R14: 000055ddf42d0d98 R15: 00007f80b6fab040
> [76613.188129]  </TASK>
>
> Fix this by simply changing key type from int to u32.
>
> Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP")
> Reported-by: Jordy Zomer <jordyzomer@google.com>
> Suggested-by: Jordy Zomer <jordyzomer@google.com>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

Nice find!

Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
diff mbox series

Patch

diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c
index e1c526f97ce3..afa457506274 100644
--- a/net/xdp/xskmap.c
+++ b/net/xdp/xskmap.c
@@ -224,7 +224,7 @@  static long xsk_map_delete_elem(struct bpf_map *map, void *key)
 	struct xsk_map *m = container_of(map, struct xsk_map, map);
 	struct xdp_sock __rcu **map_entry;
 	struct xdp_sock *old_xs;
-	int k = *(u32 *)key;
+	u32 k = *(u32 *)key;
 
 	if (k >= map->max_entries)
 		return -EINVAL;