ath10k: prevent debugfs mmio access crash kernel

It was possible to force an out of bounds MMIO
read/write via debugfs. E.g. on QCA988X this could
be triggered with:

 echo 0x2080e0 | tee /sys/kernel/debug/ieee80211/*/ath10k/reg_addr
 cat /sys/kernel/debug/ieee80211/*/ath10k/reg_value

 BUG: unable to handle kernel paging request at ffffc90001e080e0
 IP: [<ffffffff8135c860>] ioread32+0x40/0x50
 ...
 Call Trace:
  [<ffffffffa00d0c7f>] ? ath10k_pci_read32+0x4f/0x70 [ath10k_pci]
  [<ffffffffa0080f50>] ath10k_reg_value_read+0x90/0xf0 [ath10k_core]
  [<ffffffff8115c2c1>] ? handle_mm_fault+0xa91/0x1050
  [<ffffffff81189758>] __vfs_read+0x28/0xe0
  [<ffffffff812e4694>] ? security_file_permission+0x84/0xa0
  [<ffffffff81189ce3>] ? rw_verify_area+0x53/0x100
  [<ffffffff81189e1a>] vfs_read+0x8a/0x140
  [<ffffffff8118acb9>] SyS_read+0x49/0xb0
  [<ffffffff8104e39c>] ? trace_do_page_fault+0x3c/0xc0
  [<ffffffff8196596e>] system_call_fastpath+0x12/0x71

Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
index ea656e011a96e195d4513e41a482a40bab07df42..41765172297ceb4150e4f9e6c0066bab3eeb41f3 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -479,6 +479,12 @@ void ath10k_pci_write32(struct ath10k *ar, u32 offset, u32 value)
        struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
        int ret;
 
+       if (unlikely(offset + sizeof(value) > ar_pci->mem_len)) {
+               ath10k_warn(ar, "refusing to write mmio out of bounds at 0x%08x - 0x%08zx (max 0x%08zx)\n",
+                           offset, offset + sizeof(value), ar_pci->mem_len);
+               return;
+       }
+
        ret = ath10k_pci_wake(ar);
        if (ret) {
                ath10k_warn(ar, "failed to wake target for write32 of 0x%08x at 0x%08x: %d\n",
@@ -496,6 +502,12 @@ u32 ath10k_pci_read32(struct ath10k *ar, u32 offset)
        u32 val;
        int ret;
 
+       if (unlikely(offset + sizeof(val) > ar_pci->mem_len)) {
+               ath10k_warn(ar, "refusing to read mmio out of bounds at 0x%08x - 0x%08zx (max 0x%08zx)\n",
+                           offset, offset + sizeof(val), ar_pci->mem_len);
+               return 0;
+       }
+
        ret = ath10k_pci_wake(ar);
        if (ret) {
                ath10k_warn(ar, "failed to wake target for read32 at 0x%08x: %d\n",
@@ -2679,6 +2691,7 @@ static int ath10k_pci_claim(struct ath10k *ar)
        pci_set_master(pdev);
 
        /* Arrange for access to Target SoC registers. */
+       ar_pci->mem_len = pci_resource_len(pdev, BAR_NUM);
        ar_pci->mem = pci_iomap(pdev, BAR_NUM, 0);
        if (!ar_pci->mem) {
                ath10k_err(ar, "failed to iomap BAR%d\n", BAR_NUM);

diff --git a/drivers/net/wireless/ath/ath10k/pci.h b/drivers/net/wireless/ath/ath10k/pci.h
index d7696ddc03c42b2b2622913f9c42674f22f84039..eea0a0170b00ffc2fbf508f8480f380c47875b36 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/pci.h
+++ b/drivers/net/wireless/ath/ath10k/pci.h
@@ -162,6 +162,7 @@ struct ath10k_pci {
        struct device *dev;
        struct ath10k *ar;
        void __iomem *mem;
+       size_t mem_len;
 
        /*
         * Number of MSI interrupts granted, 0 --> using legacy PCI line