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Subject[PATCH] ath9k: Fix kernel NULL pointer dereference during ath_reset_internal()
Date
Function ath9k_hw_reset() is dereferencing chan structure pointer, so it
needs to be non-NULL pointer.

Function ath9k_stop() already contains code which sets ah->curchan to valid
non-NULL pointer prior calling ath9k_hw_reset() function.

Add same code pattern also into ath_reset_internal() function to prevent
kernel NULL pointer dereference in ath9k_hw_reset() function.

This change fixes kernel NULL pointer dereference in ath9k_hw_reset() which
is caused by calling ath9k_hw_reset() from ath_reset_internal() with NULL
chan structure.

[ 45.334305] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
[ 45.344417] Mem abort info:
[ 45.347301] ESR = 0x96000005
[ 45.350448] EC = 0x25: DABT (current EL), IL = 32 bits
[ 45.356166] SET = 0, FnV = 0
[ 45.359350] EA = 0, S1PTW = 0
[ 45.362596] Data abort info:
[ 45.365756] ISV = 0, ISS = 0x00000005
[ 45.369735] CM = 0, WnR = 0
[ 45.372814] user pgtable: 4k pages, 39-bit VAs, pgdp=000000000685d000
[ 45.379663] [0000000000000008] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
[ 45.388856] Internal error: Oops: 96000005 [#1] SMP
[ 45.393897] Modules linked in: ath9k ath9k_common ath9k_hw
[ 45.399574] CPU: 1 PID: 309 Comm: kworker/u4:2 Not tainted 5.12.0-rc2-dirty #785
[ 45.414746] Workqueue: phy0 ath_reset_work [ath9k]
[ 45.419713] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
[ 45.425910] pc : ath9k_hw_reset+0xc4/0x1c48 [ath9k_hw]
[ 45.431234] lr : ath9k_hw_reset+0xc0/0x1c48 [ath9k_hw]
[ 45.436548] sp : ffffffc0118dbca0
[ 45.439961] x29: ffffffc0118dbca0 x28: 0000000000000000
[ 45.445442] x27: ffffff800dee4080 x26: 0000000000000000
[ 45.450923] x25: ffffff800df9b9d8 x24: 0000000000000000
[ 45.456404] x23: ffffffc0115f6000 x22: ffffffc008d0d408
[ 45.461885] x21: ffffff800dee5080 x20: ffffff800df9b9d8
[ 45.467366] x19: 0000000000000000 x18: 0000000000000000
[ 45.472846] x17: 0000000000000000 x16: 0000000000000000
[ 45.478326] x15: 0000000000000010 x14: ffffffffffffffff
[ 45.483807] x13: ffffffc0918db94f x12: ffffffc011498720
[ 45.489289] x11: 0000000000000003 x10: ffffffc0114806e0
[ 45.494770] x9 : ffffffc01014b2ec x8 : 0000000000017fe8
[ 45.500251] x7 : c0000000ffffefff x6 : 0000000000000001
[ 45.505733] x5 : 0000000000000000 x4 : 0000000000000000
[ 45.511213] x3 : 0000000000000000 x2 : ffffff801fece870
[ 45.516693] x1 : ffffffc00eded000 x0 : 000000000000003f
[ 45.522174] Call trace:
[ 45.524695] ath9k_hw_reset+0xc4/0x1c48 [ath9k_hw]
[ 45.529653] ath_reset_internal+0x1a8/0x2b8 [ath9k]
[ 45.534696] ath_reset_work+0x2c/0x40 [ath9k]
[ 45.539198] process_one_work+0x210/0x480
[ 45.543339] worker_thread+0x5c/0x510
[ 45.547115] kthread+0x12c/0x130
[ 45.550445] ret_from_fork+0x10/0x1c
[ 45.554138] Code: 910922c2 9117e021 95ff0398 b4000294 (b9400a61)
[ 45.560430] ---[ end trace 566410ba90b50e8b ]---
[ 45.565193] Kernel panic - not syncing: Oops: Fatal exception in interrupt
[ 45.572282] SMP: stopping secondary CPUs
[ 45.576331] Kernel Offset: disabled
[ 45.579924] CPU features: 0x00040002,0000200c
[ 45.584416] Memory Limit: none
[ 45.587564] Rebooting in 3 seconds..

Signed-off-by: Pali Rohár <pali@kernel.org>
Cc: stable@vger.kernel.org
---
drivers/net/wireless/ath/ath9k/main.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 45f6402478b5..97c3a53f9cef 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -307,6 +307,11 @@ static int ath_reset_internal(struct ath_softc *sc, struct ath9k_channel *hchan)
hchan = ah->curchan;
}

+ if (!hchan) {
+ fastcc = false;
+ hchan = ath9k_cmn_get_channel(sc->hw, ah, &sc->cur_chan->chandef);
+ }
+
if (!ath_prepare_reset(sc))
fastcc = false;

--
2.20.1
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