[PATCH] staging: rtl8723bs: fix RX buffer OOB write from device-reported length

["Tianchu Chen" <tianchu.chen@linux.dev>]

From: Tianchu Chen <flynnnchen@tencent.com>

sd_recv_rxfifo() trusts the device-reported RX0_REQ_LEN value
(hal->SdioRxFIFOSize, a u16 read from the card via CMD52) as the
size of the next RX packet and passes it to sdio_read_port(), which
copies that many bytes into the recvbuf skb whose data area is only
MAX_RECVBUF_SZ (10240) bytes. A bogus device on SDIO can report up to
65535 bytes, causing a heap overflow of up to ~55KB past the skb
buffer.

Bail out when the RX0_REQ_LEN exceeds MAX_RECVBUF_SZ. This is expected
to keep behavior unchanged on normal devices.

Discovered by Atuin - Automated Vulnerability Discovery Engine.

Fixes: 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Tianchu Chen <flynnnchen@tencent.com>
---

Test Report
=============================================================
Device: Wintel CX-W8

Cmdline: nokaslr no_hash_pointers randomize_kstack_offset=0 norandmaps
mitigations=off slub_debug=FZP 

Method: An oversized OOB RX packet filled with "RTL8723B-RXOVF" pattern has
been sent via sdio bus.

Result: Kernel reports object corruption on an unrelated RCU-reclaim path:
redzone and object-padding overwritten with the test pattern.

[  973.253606] CPU: 1 UID: 0 PID: 54 Comm: kworker/u17:2 Tainted: G    B   WC         6.12.94+deb13-amd64 #1  Debian 6.12.94-1
[  973.253635] Tainted: [B]=BAD_PAGE, [W]=WARN, [C]=CRAP
[  973.253651] Hardware name: Insyde Intel CX-W8/Intel CX-W8, BIOS M.W8RAAA01 04/17/2015
[  973.253668] Workqueue: kvfree_rcu_reclaim kfree_rcu_work
[  973.253698] RIP: 0010:object_err+0x1d2/0x1df
[  973.253722] Code: 1a 29 c1 48 8d 54 05 00 48 c7 c6 13 ba 4f 82 48 c7 c7 fc 5f 4e 82 e8 6d fb ff ff be 01 00 00 00 bf 05 00 00 00 e8 de 60 40 ff <0f> 0b 5b 5d 41 5c 41 5d c3 cc cc cc cc 49 89 d7 48 8b 0c 24 4c 89
[  973.253744] RSP: 0018:ffffc90000217be0 EFLAGS: 00010046
[  973.253765] RAX: 0000000000000000 RBX: ffff888001045580 RCX: 0000000000000027
[  973.253783] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88807b8a1780
[  973.253800] RBP: ffff8880191c8040 R08: 0000000000000000 R09: ffffc90000217a60
[  973.253816] R10: ffffffff82cb43c8 R11: 0000000000000003 R12: ffff8880191c8000
[  973.253832] R13: ffffea0000647200 R14: ffffea0000647200 R15: ffff8880191c8040
[  973.253849] FS:  0000000000000000(0000) GS:ffff88807b880000(0000) knlGS:0000000000000000
[  973.253867] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  973.253884] CR2: 00007ffff7dfe350 CR3: 0000000005622000 CR4: 00000000001026f0
[  973.253901] Call Trace:
[  973.253918]  <TASK>
[  973.253939]  check_bytes_and_report.cold+0x66/0x84
[  973.253967]  check_object+0x17c/0x310
[  973.253994]  free_to_partial_list+0x1cd/0x490
[  973.254017]  ? kvfree_rcu_bulk+0x16a/0x1a0
[  973.254040]  kmem_cache_free_bulk.part.0+0x3b1/0x3d0
[  973.254064]  ? kvfree_rcu_bulk+0x16a/0x1a0
[  973.254086]  ? update_entity_lag+0x1b/0x90
[  973.254113]  kvfree_rcu_bulk+0x16a/0x1a0
[  973.254137]  kfree_rcu_work+0x100/0x1b0
[  973.254160]  ? __schedule+0x50d/0xc00
[  973.254184]  process_one_work+0x174/0x330
[  973.254210]  worker_thread+0x191/0x2f0
[  973.254234]  ? __pfx_worker_thread+0x10/0x10
[  973.254257]  kthread+0xcf/0x100
[  973.254279]  ? __pfx_kthread+0x10/0x10
[  973.254299]  ret_from_fork+0x31/0x50
[  973.254322]  ? __pfx_kthread+0x10/0x10
[  973.254343]  ret_from_fork_asm+0x1a/0x30
[  973.254369]  </TASK>
[  973.254385] ---[ end trace 0000000000000000 ]---
[  973.254404] FIX kmalloc-cg-192: Restoring Left Redzone 0xffff8880191c8000-0xffff8880191c803f=0xcc
[  973.254426] [Right Redzone overwritten] 0xffff8880191c8100-0xffff8880191c8107 @offset=256. First byte 0x2d instead of 0xcc
[  973.254447] FIX kmalloc-cg-192: Restoring Right Redzone 0xffff8880191c8100-0xffff8880191c8107=0xcc
[  973.254465] [Object padding overwritten] 0xffff8880191c8110-0xffff8880191c813f @offset=272. First byte 0x52 instead of 0x5a
[  973.254485] =============================================================================
[  973.254500] BUG kmalloc-cg-192 (Tainted: G    B   WC        ): Object corrupt
[  973.254517] -----------------------------------------------------------------------------
[  973.254517] 
[  973.254560] Slab 0xffffea0000647200 objects=25 used=12 fp=0xffff8880191c9e40 flags=0xfffffc0000240(workingset|head|node=0|zone=1|lastcpupid=0x1fffff)
[  973.254587] Object 0xffff8880191c8040 @offset=64 fp=0xffff8880191c8400
[  973.254587] 
[  973.254606] Redzone  ffff8880191c8000: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
[  973.254624] Redzone  ffff8880191c8010: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
[  973.254641] Redzone  ffff8880191c8020: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
[  973.254659] Redzone  ffff8880191c8030: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
[  973.254694] Object   ffff8880191c8050: 56 46 21 52 54 4c 38 37 32 33 42 2d 52 58 4f 56  VF!RTL8723B-RXOV
[  973.254711] Object   ffff8880191c8060: 46 21 52 54 4c 38 37 32 33 42 2d 52 58 4f 56 46  F!RTL8723B-RXOVF
[  973.254728] Object   ffff8880191c8070: 21 52 54 4c 38 37 32 33 42 2d 52 58 4f 56 46 21  !RTL8723B-RXOVF!
[  973.254745] Object   ffff8880191c8080: 52 54 4c 38 37 32 33 42 2d 52 58 4f 56 46 21 52  RTL8723B-RXOVF!R
[  973.254762] Object   ffff8880191c8090: 54 4c 38 37 32 33 42 2d 52 58 4f 56 46 21 52 54  TL8723B-RXOVF!RT
[  973.254779] Object   ffff8880191c80a0: 4c 38 37 32 33 42 2d 52 58 4f 56 46 21 52 54 4c  L8723B-RXOVF!RTL
[  973.254796] Object   ffff8880191c80b0: 38 37 32 33 42 2d 52 58 4f 56 46 21 52 54 4c 38  8723B-RXOVF!RTL8
[  973.254812] Object   ffff8880191c80c0: 37 32 33 42 2d 52 58 4f 56 46 21 52 54 4c 38 37  723B-RXOVF!RTL87
[  973.254829] Object   ffff8880191c80d0: 32 33 42 2d 52 58 4f 56 46 21 52 54 4c 38 37 32  23B-RXOVF!RTL872
[  973.254846] Object   ffff8880191c80e0: 33 42 2d 52 58 4f 56 46 21 52 54 4c 38 37 32 33  3B-RXOVF!RTL8723
[  973.254863] Object   ffff8880191c80f0: 42 2d 52 58 4f 56 46 21 52 54 4c 38 37 32 33 42  B-RXOVF!RTL8723B
[  973.254880] Redzone  ffff8880191c8100: cc cc cc cc cc cc cc cc                          ........
[  973.254917] Padding  ffff8880191c8110: 52 58 4f 56 46 21 52 54 4c 38 37 32 33 42 2d 52  RXOVF!RTL8723B-R
[  973.254953] Padding  ffff8880191c8130: 4f 56 46 21 52 54 4c 38 37 32 33 42 2d 52 58 4f  OVF!RTL8723B-RXO


 drivers/staging/rtl8723bs/hal/sdio_ops.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/staging/rtl8723bs/hal/sdio_ops.c b/drivers/staging/rtl8723bs/hal/sdio_ops.c
index da2d9088ab5ac..b7a4ab0bedc90 100644
--- a/drivers/staging/rtl8723bs/hal/sdio_ops.c
+++ b/drivers/staging/rtl8723bs/hal/sdio_ops.c
@@ -644,6 +644,13 @@ static struct recv_buf *sd_recv_rxfifo(struct adapter *adapter, u32 size)
 	struct recv_priv *recv_priv;
 	struct recv_buf	*recvbuf;
 
+	/* RX0_REQ_LEN is device-reported; the skb buffer is only
+	 * MAX_RECVBUF_SZ bytes, reject bogus lengths instead of
+	 * overflowing past it.
+	 */
+	if (size > MAX_RECVBUF_SZ)
+		return NULL;
+
 	/*  Patch for some SDIO Host 4 bytes issue */
 	/*  ex. RK3188 */
 	readsize = round_up(size, 4);
-- 
2.51.0