There may be a potential kernel crash risk if 'skb->len - MTK_COREDUMP_END_LEN'
value is less than 0 when doing memcmp in btmtk_process_coredump().
Check the value is valid before doing memcmp.
[ 215.021695] Unable to handle kernel paging request at virtual address ffffff939fffd3c5
[ 215.021781] Mem abort info:
[ 215.021805] ESR = 0x96000005
[ 215.021833] EC = 0x25: DABT (current EL), IL = 32 bits
[ 215.021861] SET = 0, FnV = 0
[ 215.021875] EA = 0, S1PTW = 0
[ 215.021886] Data abort info:
[ 215.021899] ISV = 0, ISS = 0x00000005
[ 215.021912] CM = 0, WnR = 0
[ 215.021929] swapper pgtable: 4k pages, 39-bit VAs, pgdp=00000000410de000
[ 215.021943] [ffffff939fffd3c5] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
[ 215.021979] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 215.022496] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.186 #3 (HASH:ad23 4)
[ 215.022511] Hardware name: MediaTek Tomato board (DT)
[ 215.022530] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--)
[ 215.022556] pc : __pi_memcmp+0xd0/0x1b8
[ 215.022579] lr : btmtk_process_coredump+0xb0/0x5f8 [btmtk]
[ 215.022593] sp : ffffffc010003d40
[ 215.022607] x29: ffffffc010003d40 x28: 0000000000000006
[ 215.022633] x27: ffffffda696350c0 x26: 0000000000000002
[ 215.022659] x25: 00000000000003ff x24: ffffff9360cca804
[ 215.022685] x23: 0000000000000000 x22: ffffff9365638500
[ 215.022710] x21: ffffff9365638700 x20: 0000000000000000
[ 215.022736] x19: ffffff936002e000 x18: 0000000000000000
[ 215.022761] x17: 0000000000000180 x16: ffffffda6881b8b4
[ 215.022787] x15: 0000000000000001 x14: 0000000000002d00
[ 215.022812] x13: 0000000000060000 x12: 0000000000000181
[ 215.022837] x11: 0000000000000006 x10: fffffffffffffffd
[ 215.022862] x9 : 0000000000000006 x8 : 0000000000000003
[ 215.022887] x7 : 0000000000000000 x6 : 0000000000000000
[ 215.022913] x5 : ffffff93656387b8 x4 : 0000000000000000
[ 215.022938] x3 : ffffffc010003c18 x2 : 0000000000000006
[ 215.022963] x1 : ffffffda09d4124a x0 : ffffff939fffd3c5
[ 215.022989] Call trace:
[ 215.023012] __pi_memcmp+0xd0/0x1b8
[ 215.023053] btusb_recv_acl_mtk+0x64/0x90 [btusb (HASH:dc6b 5)]
[ 215.023087] btusb_recv_bulk+0x118/0x170 [btusb (HASH:dc6b 5)]
[ 215.023121] btusb_bulk_complete+0x8c/0x148 [btusb (HASH:dc6b 5)]
[ 215.023144] __usb_hcd_giveback_urb+0xbc/0x148
[ 215.023164] usb_giveback_urb_bh+0xb4/0x190
[ 215.023184] tasklet_action_common+0x98/0x1a0
[ 215.023201] tasklet_action+0x2c/0x38
[ 215.023220] __do_softirq+0xe0/0x38c
[ 215.023241] invoke_softirq+0x34/0x6c
[ 215.023258] irq_exit+0x6c/0xb0
[ 215.023279] __handle_domain_irq+0x98/0xd4
[ 215.023296] gic_handle_irq+0x5c/0x11c
[ 215.023313] el1_irq+0xd0/0x180
[ 215.023332] cpuidle_enter_state+0xac/0x338
[ 215.023349] cpuidle_enter+0x40/0x70
[ 215.023366] do_idle+0x150/0x278
[ 215.023384] cpu_startup_entry+0x2c/0x58
[ 215.023401] rest_init+0xdc/0xec
[ 215.023419] arch_call_rest_init+0x18/0x24
[ 215.023435] start_kernel+0x334/0x400
[ 215.023460] Code: 91002129 eb09010a 9a89810b cb0b0042 (38401403)
[ 215.023478] ---[ end trace 28668fd20c7a90cd ]
Fixes: 2822cd0173ad ("Bluetooth: btusb: mediatek: add MediaTek devcoredump support")
Signed-off-by: Chris Lu <chris.lu@xxxxxxxxxxxx>
Co-developed-by: Sean Wang <sean.wang@xxxxxxxxxxxx>
Signed-off-by: Sean Wang <sean.wang@xxxxxxxxxxxx>
---
drivers/bluetooth/btmtk.c | 12 ++++++------
drivers/bluetooth/btmtk.h | 1 +
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 786f775196ae..aaabb732082c 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -395,12 +395,12 @@ int btmtk_process_coredump(struct hci_dev *hdev, struct sk_buff *skb)
/* Mediatek coredump data would be more than MTK_COREDUMP_NUM */
if (data->cd_info.cnt > MTK_COREDUMP_NUM &&
- skb->len > sizeof(MTK_COREDUMP_END) &&
- !memcmp((char *)&skb->data[skb->len - sizeof(MTK_COREDUMP_END)],
- MTK_COREDUMP_END, sizeof(MTK_COREDUMP_END) - 1)) {
- bt_dev_info(hdev, "Mediatek coredump end");
- hci_devcd_complete(hdev);
- }
+ skb->len > MTK_COREDUMP_END_LEN)
+ if (!memcmp((char *)&skb->data[skb->len - MTK_COREDUMP_END_LEN],
+ MTK_COREDUMP_END, MTK_COREDUMP_END_LEN - 1)) {
+ bt_dev_info(hdev, "Mediatek coredump end");
+ hci_devcd_complete(hdev);
+ }
break;
}
diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
index 68309dfe076a..56f5502baadf 100644
--- a/drivers/bluetooth/btmtk.h
+++ b/drivers/bluetooth/btmtk.h
@@ -24,6 +24,7 @@
#define MTK_COREDUMP_SIZE (1024 * 1000)
#define MTK_COREDUMP_END "coredump end"
+#define MTK_COREDUMP_END_LEN (sizeof(MTK_COREDUMP_END))
#define MTK_COREDUMP_NUM 255
enum {
--
2.18.0
