From: Mohammed Shafi Shajakhan <[email protected]>
'ath10k_htt_tx_free_cont_txbuf' and 'ath10k_htt_tx_free_cont_frag_desc'
have NULL pointer checks to avoid crash if they are called twice
but this is as of now not sufficient as these pointers are not assigned
to NULL once the contiguous DMA memory allocation is freed, fix this.
Though this may not be hit with the explicity check of state variable
'tx_mem_allocated' check, good to have this addressed as well.
Below BUG_ON is hit when the above scenario is simulated
with kernel debugging enabled
page:f6d09a00 count:0 mapcount:-127 mapping: (null)
index:0x0
flags: 0x40000000()
page dumped because: VM_BUG_ON_PAGE(page_ref_count(page)
== 0)
------------[ cut here ]------------
kernel BUG at ./include/linux/mm.h:445!
invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
EIP is at put_page_testzero.part.88+0xd/0xf
Call Trace:
[<c118a2cc>] __free_pages+0x3c/0x40
[<c118a30e>] free_pages+0x3e/0x50
[<c10222b4>] dma_generic_free_coherent+0x24/0x30
[<f8c1d9a8>] ath10k_htt_tx_free_cont_txbuf+0xf8/0x140
[<f8c1e2a9>] ath10k_htt_tx_destroy+0x29/0xa0
[<f8c143e0>] ath10k_core_destroy+0x60/0x80 [ath10k_core]
[<f8acd7e9>] ath10k_pci_remove+0x79/0xa0 [ath10k_pci]
[<c13ed7a8>] pci_device_remove+0x38/0xb0
[<c14d3492>] __device_release_driver+0x72/0x100
[<c14d36b7>] driver_detach+0x97/0xa0
[<c14d29c0>] bus_remove_driver+0x40/0x80
[<c14d427a>] driver_unregister+0x2a/0x60
[<c13ec768>] pci_unregister_driver+0x18/0x70
[<f8aced4f>] ath10k_pci_exit+0xd/0x2be [ath10k_pci]
[<c1101e78>] SyS_delete_module+0x158/0x210
[<c11b34f1>] ? __might_fault+0x41/0xa0
[<c11b353b>] ? __might_fault+0x8b/0xa0
[<c1001a4b>] do_fast_syscall_32+0x9b/0x1c0
[<c178da34>] sysenter_past_esp+0x45/0x74
Signed-off-by: Mohammed Shafi Shajakhan <[email protected]>
---
drivers/net/wireless/ath/ath10k/htt_tx.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index 27e49db..86b427f 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -239,6 +239,7 @@ static void ath10k_htt_tx_free_cont_txbuf(struct ath10k_htt *htt)
size = htt->max_num_pending_tx * sizeof(struct ath10k_htt_txbuf);
dma_free_coherent(ar->dev, size, htt->txbuf.vaddr, htt->txbuf.paddr);
+ htt->txbuf.vaddr = NULL;
}
static int ath10k_htt_tx_alloc_cont_txbuf(struct ath10k_htt *htt)
@@ -268,6 +269,7 @@ static void ath10k_htt_tx_free_cont_frag_desc(struct ath10k_htt *htt)
size,
htt->frag_desc.vaddr,
htt->frag_desc.paddr);
+ htt->frag_desc.vaddr = NULL;
}
static int ath10k_htt_tx_alloc_cont_frag_desc(struct ath10k_htt *htt)
--
1.9.1
Mohammed Shafi Shajakhan <[email protected]> wrote:
> From: Mohammed Shafi Shajakhan <[email protected]>
>
> 'ath10k_htt_tx_free_cont_txbuf' and 'ath10k_htt_tx_free_cont_frag_desc'
> have NULL pointer checks to avoid crash if they are called twice
> but this is as of now not sufficient as these pointers are not assigned
> to NULL once the contiguous DMA memory allocation is freed, fix this.
> Though this may not be hit with the explicity check of state variable
> 'tx_mem_allocated' check, good to have this addressed as well.
>
> Below BUG_ON is hit when the above scenario is simulated
> with kernel debugging enabled
>
> page:f6d09a00 count:0 mapcount:-127 mapping: (null)
> index:0x0
> flags: 0x40000000()
> page dumped because: VM_BUG_ON_PAGE(page_ref_count(page)
> == 0)
> ------------[ cut here ]------------
> kernel BUG at ./include/linux/mm.h:445!
> invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
> EIP is at put_page_testzero.part.88+0xd/0xf
> Call Trace:
> [<c118a2cc>] __free_pages+0x3c/0x40
> [<c118a30e>] free_pages+0x3e/0x50
> [<c10222b4>] dma_generic_free_coherent+0x24/0x30
> [<f8c1d9a8>] ath10k_htt_tx_free_cont_txbuf+0xf8/0x140
>
> [<f8c1e2a9>] ath10k_htt_tx_destroy+0x29/0xa0
>
> [<f8c143e0>] ath10k_core_destroy+0x60/0x80 [ath10k_core]
> [<f8acd7e9>] ath10k_pci_remove+0x79/0xa0 [ath10k_pci]
> [<c13ed7a8>] pci_device_remove+0x38/0xb0
> [<c14d3492>] __device_release_driver+0x72/0x100
> [<c14d36b7>] driver_detach+0x97/0xa0
> [<c14d29c0>] bus_remove_driver+0x40/0x80
> [<c14d427a>] driver_unregister+0x2a/0x60
> [<c13ec768>] pci_unregister_driver+0x18/0x70
> [<f8aced4f>] ath10k_pci_exit+0xd/0x2be [ath10k_pci]
> [<c1101e78>] SyS_delete_module+0x158/0x210
> [<c11b34f1>] ? __might_fault+0x41/0xa0
> [<c11b353b>] ? __might_fault+0x8b/0xa0
> [<c1001a4b>] do_fast_syscall_32+0x9b/0x1c0
> [<c178da34>] sysenter_past_esp+0x45/0x74
>
> Signed-off-by: Mohammed Shafi Shajakhan <[email protected]>
Patch applied to ath-next branch of ath.git, thanks.
02a9e08d7374 ath10k: Avoid potential page alloc BUG_ON in tx free path
--
https://patchwork.kernel.org/patch/9463923/
Documentation about submitting wireless patches and checking status
from patchwork:
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches