[RESEND PATCH -next v2] usb: xhci: do not free an empty cmd ring
From: Hongyu Xie
Date: Wed Apr 12 2023 - 20:52:11 EST
It was first found on HUAWEI Kirin 9006C platform with a builtin xhci
controller during stress cycle test(stress-ng, glmark2, x11perf, S4...).
phase one:
[26788.706878] PM: dpm_run_callback(): platform_pm_thaw+0x0/0x68 returns -12
[26788.706878] PM: Device xhci-hcd.1.auto failed to thaw async: error -12
...
phase two:
[28650.583496] [2023:01:19 04:43:29]Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
...
[28650.583526] user pgtable: 4k pages, 39-bit VAs, pgdp=000000027862a000
[28650.583557] [0000000000000028] pgd=0000000000000000
...
[28650.583587] pc : xhci_suspend+0x154/0x5b0
[28650.583618] lr : xhci_suspend+0x148/0x5b0
[28650.583618] sp : ffffffc01c7ebbd0
[28650.583618] x29: ffffffc01c7ebbd0 x28: ffffffec834d0000
[28650.583618] x27: ffffffc0106a3cc8 x26: ffffffb2c540c848
[28650.583618] x25: 0000000000000000 x24: ffffffec82ee30b0
[28650.583618] x23: ffffffb43b31c2f8 x22: 0000000000000000
[28650.583618] x21: 0000000000000000 x20: ffffffb43b31c000
[28650.583648] x19: ffffffb43b31c2a8 x18: 0000000000000001
[28650.583648] x17: 0000000000000803 x16: 00000000fffffffe
[28650.583648] x15: 0000000000001000 x14: ffffffb150b67e00
[28650.583648] x13: 00000000f0000000 x12: 0000000000000001
[28650.583648] x11: 0000000000000000 x10: 0000000000000a80
[28650.583648] x9 : ffffffc01c7eba00 x8 : ffffffb43ad10ae0
[28650.583648] x7 : ffffffb84cd98dc0 x6 : 0000000cceb6a101
[28650.583679] x5 : 00ffffffffffffff x4 : 0000000000000001
[28650.583679] x3 : 0000000000000011 x2 : 0000000000e2cfa8
[28650.583679] x1 : 00000000823535e1 x0 : 0000000000000000
gdb:
(gdb) l *(xhci_suspend+0x154)
0xffffffc010b6cd44 is in xhci_suspend (/.../drivers/usb/host/xhci.c:854).
849 {
850 struct xhci_ring *ring;
851 struct xhci_segment *seg;
852
853 ring = xhci->cmd_ring;
854 seg = ring->deq_seg;
(gdb) disassemble 0xffffffc010b6cd44
...
0xffffffc010b6cd40 <+336>: ldr x22, [x19, #160]
0xffffffc010b6cd44 <+340>: ldr x20, [x22, #40]
0xffffffc010b6cd48 <+344>: mov w1, #0x0 // #0
During phase one, platform_pm_thaw called xhci_plat_resume which called
xhci_resume. The rest possible calling routine might be
xhci_resume->xhci_init->xhci_mem_init, and xhci->cmd_ring was cleaned in
xhci_mem_cleanup before xhci_mem_init returned -ENOMEM.
During phase two, systemd was tring to hibernate again and called
xhci_suspend, then xhci_clear_command_ring dereferenced xhci->cmd_ring
which was already NULL.
So if xhci->cmd_ring is NULL, xhci_clear_command_ring just return.
Fixes: 898213200cba ("xhci: Fix command ring replay after resume.")
Cc: stable@xxxxxxxxxxxxxxx # 2.6.27+
Co-developed-by: sunke <sunke@xxxxxxxxxx>
Signed-off-by: sunke <sunke@xxxxxxxxxx>
Signed-off-by: Hongyu Xie <xiehongyu1@xxxxxxxxxx>
---
drivers/usb/host/xhci.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6183ce8574b1..faa0a63671f6 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -920,6 +920,11 @@ static void xhci_clear_command_ring(struct xhci_hcd *xhci)
struct xhci_ring *ring;
struct xhci_segment *seg;
+ if (!xhci->cmd_ring) {
+ xhci_err(xhci, "Empty cmd ring");
+ return;
+ }
+
ring = xhci->cmd_ring;
seg = ring->deq_seg;
do {
--
2.34.1