[PATCH] scsi: sd: fix crashes in sd_resume_runtime

Miles Chen
2021-10-15T07:47:07Z

After merging commit ed4246d37f3b ("scsi: sd: REQUEST SENSE for
BLIST_IGN_MEDIA_CHANGE devices in runtime_resume()"), I hit the
following crash on my device.

static int sd_resume_runtime(struct device *dev)
{
struct scsi_disk *sdkp = dev_get_drvdata(dev);
struct scsi_device *sdp = sdkp->device; // sdkp == NULL and crash

if (sdp->ignore_media_change) {
...
}

I checked sd_resume() and found that sdkp is possbile to be NULL, and
there is a null pointer test in sd_resume() for this case.
To fix this crash, follow sd_resume() to test if sdkp is NULL
before dereferencing it.

Crash:
[ 4.695171][ T151] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
[ 4.696591][ T151] Mem abort info:
[ 4.697919][ T151] ESR = 0x96000005
[ 4.699692][ T151] EC = 0x25: DABT (current EL), IL = 32 bits
[ 4.701990][ T151] SET = 0, FnV = 0
[ 4.702513][ T151] EA = 0, S1PTW = 0
[ 4.704431][ T151] FSC = 0x05: level 1 translation fault
[ 4.705254][ T151] Data abort info:
[ 4.705806][ T151] ISV = 0, ISS = 0x00000005
[ 4.706484][ T151] CM = 0, WnR = 0
[ 4.707048][ T151] [0000000000000008] user address but active_mm is swapper
[ 4.710577][ T151] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 4.832361][ T151] Kernel Offset: 0x12acc80000 from 0xffffffc010000000
[ 4.833254][ T151] PHYS_OFFSET: 0x40000000
[ 4.833814][ T151] pstate: 80400005 (Nzcv daif +PAN -UAO)
[ 4.834546][ T151] pc : sd_resume_runtime+0x20/0x14c
[ 4.835227][ T151] lr : scsi_runtime_resume+0x84/0xe4
[ 4.835916][ T151] sp : ffffffc0110db8d0
[ 4.836450][ T151] x29: ffffffc0110db8d0 x28: 0000000000000001
[ 4.837258][ T151] x27: ffffff80c0bd1ac0 x26: ffffff80c0bd1ad0
[ 4.838063][ T151] x25: ffffff80cea7e448 x24: ffffffd2bf961000
[ 4.838867][ T151] x23: ffffffd2be69f838 x22: ffffffd2bd9dfb4c
[ 4.839670][ T151] x21: 0000000000000000 x20: ffffff80cea7e000
[ 4.840474][ T151] x19: ffffff80cea7e260 x18: ffffffc0110dd078
[ 4.841277][ T151] x17: 00000000658783d9 x16: 0000000051469dac
[ 4.842081][ T151] x15: 00000000b87f6327 x14: 0000000068fd680d
[ 4.842885][ T151] x13: ffffff80c0bd2470 x12: ffffffd2bfa7f5f0
[ 4.843688][ T151] x11: 0000000000000078 x10: 0000000000000001
[ 4.844492][ T151] x9 : 00000000000000b1 x8 : ffffffd2be69f88c
[ 4.845295][ T151] x7 : ffffffd2bd9e0e5c x6 : 0000000000000000
[ 4.846099][ T151] x5 : 0000000000000080 x4 : 0000000000000001
[ 4.846902][ T151] x3 : 68fd680dfe4ebe5e x2 : 0000000000000003
[ 4.847706][ T151] x1 : ffffffd2bf7f9380 x0 : ffffff80cea7e260
[ 4.856708][ T151] die+0x16c/0x59c
[ 4.857191][ T151] __do_kernel_fault+0x1e8/0x210
[ 4.857833][ T151] do_page_fault+0xa4/0x654
[ 4.858418][ T151] do_translation_fault+0x6c/0x1b0
[ 4.859083][ T151] do_mem_abort+0x68/0x10c
[ 4.859655][ T151] el1_abort+0x40/0x64
[ 4.860182][ T151] el1h_64_sync_handler+0x54/0x88
[ 4.860834][ T151] el1h_64_sync+0x7c/0x80
[ 4.861395][ T151] sd_resume_runtime+0x20/0x14c
[ 4.862025][ T151] scsi_runtime_resume+0x84/0xe4
[ 4.862667][ T151] __rpm_callback+0x1f4/0x8cc
[ 4.863275][ T151] rpm_resume+0x7e8/0xaa4
[ 4.863836][ T151] __pm_runtime_resume+0xa0/0x110
[ 4.864489][ T151] sd_probe+0x30/0x428
[ 4.865016][ T151] really_probe+0x14c/0x500
[ 4.865602][ T151] __driver_probe_device+0xb4/0x18c
[ 4.866278][ T151] driver_probe_device+0x60/0x2c4
[ 4.866931][ T151] __device_attach_driver+0x228/0x2bc
[ 4.867630][ T151] __device_attach_async_helper+0x154/0x21c
[ 4.868398][ T151] async_run_entry_fn+0x5c/0x1c4
[ 4.869038][ T151] process_one_work+0x3ac/0x590
[ 4.869670][ T151] worker_thread+0x320/0x758
[ 4.870265][ T151] kthread+0x2e8/0x35c
[ 4.870792][ T151] ret_from_fork+0x10/0x20

Cc: Stanley Chu <stanley.chu@mediatek.com>
Fixes: ed4246d37f3b ("scsi: sd: REQUEST SENSE for BLIST_IGN_MEDIA_CHANGE devices in runtime_resume()")
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
drivers/scsi/sd.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 523bf2fdc253..fce63335084e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3683,7 +3683,12 @@ static int sd_resume(struct device *dev)
static int sd_resume_runtime(struct device *dev)
{
struct scsi_disk *sdkp = dev_get_drvdata(dev);
- struct scsi_device *sdp = sdkp->device;
+ struct scsi_device *sdp;
+
+ if (!sdkp) /* E.g.: runtime resume at the start of sd_probe() */
+ return 0;
+
+ sdp = sdkp->device;

if (sdp->ignore_media_change) {
/* clear the device's sense data */
--
2.18.0