From 02a9e08d7374f1bb680cd44a2f124793f4e7d6e7 Mon Sep 17 00:00:00 2001 From: Mohammed Shafi Shajakhan Date: Wed, 7 Dec 2016 10:30:32 +0530 Subject: ath10k: Avoid potential page alloc BUG_ON in tx free path '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: [] __free_pages+0x3c/0x40 [] free_pages+0x3e/0x50 [] dma_generic_free_coherent+0x24/0x30 [] ath10k_htt_tx_free_cont_txbuf+0xf8/0x140 [] ath10k_htt_tx_destroy+0x29/0xa0 [] ath10k_core_destroy+0x60/0x80 [ath10k_core] [] ath10k_pci_remove+0x79/0xa0 [ath10k_pci] [] pci_device_remove+0x38/0xb0 [] __device_release_driver+0x72/0x100 [] driver_detach+0x97/0xa0 [] bus_remove_driver+0x40/0x80 [] driver_unregister+0x2a/0x60 [] pci_unregister_driver+0x18/0x70 [] ath10k_pci_exit+0xd/0x2be [ath10k_pci] [] SyS_delete_module+0x158/0x210 [] ? __might_fault+0x41/0xa0 [] ? __might_fault+0x8b/0xa0 [] do_fast_syscall_32+0x9b/0x1c0 [] sysenter_past_esp+0x45/0x74 Signed-off-by: Mohammed Shafi Shajakhan Signed-off-by: Kalle Valo --- drivers/net/wireless/ath/ath10k/htt_tx.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/net/wireless/ath/ath10k/htt_tx.c') diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c index 27e49db4287a..86b427f5e2bc 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) -- cgit v1.2.3-59-g8ed1b