[PATCH v5] brcmfmac: prevent double-free on hardware-reset

[Danny van Heumen <danny@dannyvanheumen.nl>]

In case of buggy firmware, brcmfmac may perform a hardware reset. If during
reset and subsequent probing an early failure occurs, a memory region is
accidentally double-freed. With hardened memory allocation enabled, this error
will be detected.

- return early where appropriate to skip unnecessary clean-up.
- set '.freezer' pointer to NULL to prevent double-freeing under possible
  other circumstances and to re-align result under various different
  behaviors of memory allocation freeing.
- correctly claim host on func1 for disabling func2.
- after reset, do not initiate probing immediately, but rely on events.

Given a firmware crash, function 'brcmf_sdio_bus_reset' is called. It calls
'brcmf_sdiod_remove', then follows up with 'brcmf_sdiod_probe' to reinitialize
the hardware. If 'brcmf_sdiod_probe' fails to "set F1 blocksize", it exits
early, which includes calling 'brcmf_sdiod_remove'. In both cases
'brcmf_sdiod_freezer_detach' is called to free allocated '.freezer', which
has not yet been re-allocated the second time.

Stacktrace of (failing) hardware reset after firmware-crash:

Code: b9402b82 8b0202c0 eb1a02df 54000041 (d4210000)
 ret_from_fork+0x10/0x20
 kthread+0x154/0x160
 worker_thread+0x188/0x504
 process_one_work+0x1f4/0x490
 brcmf_core_bus_reset+0x34/0x44 [brcmfmac]
 brcmf_sdio_bus_reset+0x68/0xc0 [brcmfmac]
 brcmf_sdiod_probe+0x170/0x21c [brcmfmac]
 brcmf_sdiod_remove+0x48/0xc0 [brcmfmac]
 kfree+0x210/0x220
 __slab_free+0x58/0x40c
Call trace:
x2 : 0000000000000040 x1 : fffffc00002d2b80 x0 : ffff00000b4aee40
x5 : ffff8000013fa728 x4 : 0000000000000001 x3 : ffff00000b4aee00
x8 : ffff800009967ce0 x7 : ffff8000099bfce0 x6 : 00000006f8005d01
x11: ffff8000099bfce0 x10: 00000000fffff000 x9 : ffff8000083401d0
x14: 0000000000000000 x13: 657a69736b636f6c x12: 6220314620746573
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000030
x20: fffffc00002d2ba0 x19: fffffc00002d2b80 x18: 0000000000000000
x23: ffff00000b4aee00 x22: ffff00000b4aee00 x21: 0000000000000001
x26: ffff00000b4aee00 x25: ffff0000f7753705 x24: 000000000001288a
x29: ffff80000a22bbf0 x28: ffff000000401200 x27: 000000008020001a
sp : ffff80000a22bbf0
lr : kfree+0x210/0x220
pc : __slab_free+0x58/0x40c
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
Workqueue: events brcmf_core_bus_reset [brcmfmac]
Hardware name: Pine64 Pinebook Pro (DT)
CPU: 2 PID: 639 Comm: kworker/2:2 Tainted: G         C        5.16.0-0.bpo.4-arm64 #1  Debian 5.16.12-1~bpo11+1
 nvmem_rockchip_efuse industrialio_triggered_buffer videodev snd_soc_core snd_pcm_dmaengine kfifo_buf snd_pcm io_domain mc industrialio mt>
Modules linked in: snd_seq_dummy snd_hrtimer snd_seq snd_seq_device nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reje>
Internal error: Oops - BUG: 0 [#1] SMP
kernel BUG at mm/slub.c:379!

Signed-off-by: Danny van Heumen <danny@dannyvanheumen.nl>
---
 .../wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c   | 13 +++++--------
 .../net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 10 +---------
 2 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c
index ac02244a6fdf..414ee21f42e3 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c
@@ -802,6 +802,7 @@ static void brcmf_sdiod_freezer_detach(struct brcmf_sdio_dev *sdiodev)
 	if (sdiodev->freezer) {
 		WARN_ON(atomic_read(&sdiodev->freezer->freezing));
 		kfree(sdiodev->freezer);
+		sdiodev->freezer = NULL;
 	}
 }

@@ -875,13 +876,9 @@ int brcmf_sdiod_remove(struct brcmf_sdio_dev *sdiodev)

 	brcmf_sdiod_freezer_detach(sdiodev);

-	/* Disable Function 2 */
-	sdio_claim_host(sdiodev->func2);
-	sdio_disable_func(sdiodev->func2);
-	sdio_release_host(sdiodev->func2);
-
-	/* Disable Function 1 */
+	/* Disable functions 2 then 1. */
 	sdio_claim_host(sdiodev->func1);
+	sdio_disable_func(sdiodev->func2);
 	sdio_disable_func(sdiodev->func1);
 	sdio_release_host(sdiodev->func1);

@@ -911,7 +908,7 @@ int brcmf_sdiod_probe(struct brcmf_sdio_dev *sdiodev)
 	if (ret) {
 		brcmf_err("Failed to set F1 blocksize\n");
 		sdio_release_host(sdiodev->func1);
-		goto out;
+		return ret;
 	}
 	switch (sdiodev->func2->device) {
 	case SDIO_DEVICE_ID_BROADCOM_CYPRESS_4373:
@@ -933,7 +930,7 @@ int brcmf_sdiod_probe(struct brcmf_sdio_dev *sdiodev)
 	if (ret) {
 		brcmf_err("Failed to set F2 blocksize\n");
 		sdio_release_host(sdiodev->func1);
-		goto out;
+		return ret;
 	} else {
 		brcmf_dbg(SDIO, "set F2 blocksize to %d\n", f2_blksz);
 	}
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index 212fbbe1cd7e..2ed70f809097 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -4152,7 +4152,6 @@ int brcmf_sdio_get_fwname(struct device *dev, const char *ext, u8 *fw_name)

 static int brcmf_sdio_bus_reset(struct device *dev)
 {
-	int ret = 0;
 	struct brcmf_bus *bus_if = dev_get_drvdata(dev);
 	struct brcmf_sdio_dev *sdiodev = bus_if->bus_priv.sdio;

@@ -4169,14 +4168,7 @@ static int brcmf_sdio_bus_reset(struct device *dev)
 	sdio_release_host(sdiodev->func1);

 	brcmf_bus_change_state(sdiodev->bus_if, BRCMF_BUS_DOWN);
-
-	ret = brcmf_sdiod_probe(sdiodev);
-	if (ret) {
-		brcmf_err("Failed to probe after sdio device reset: ret %d\n",
-			  ret);
-	}
-
-	return ret;
+	return 0;
 }

 static const struct brcmf_bus_ops brcmf_sdio_bus_ops = {
--
2.34.1