netdev - Re: [PATCH 2/5] PCI/VPD: Use pci_read_vpd_any() in pci_vpd

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Message-ID: <88bfd6ed-f5c6-b9f9-c331-643eb0d37289@nvidia.com>
Date:   Wed, 27 Oct 2021 12:01:04 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Raju Rangoju <rajur@...lsio.com>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH 2/5] PCI/VPD: Use pci_read_vpd_any() in pci_vpd_size()


On 10/09/2021 07:22, Heiner Kallweit wrote:
> Use new function pci_read_vpd_any() to simplify the code.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
>   drivers/pci/vpd.c | 7 ++-----
>   1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
> index 286cad2a6..517789205 100644
> --- a/drivers/pci/vpd.c
> +++ b/drivers/pci/vpd.c
> @@ -57,10 +57,7 @@ static size_t pci_vpd_size(struct pci_dev *dev)
>   	size_t off = 0, size;
>   	unsigned char tag, header[1+2];	/* 1 byte tag, 2 bytes length */
>   
> -	/* Otherwise the following reads would fail. */
> -	dev->vpd.len = PCI_VPD_MAX_SIZE;
> -
> -	while (pci_read_vpd(dev, off, 1, header) == 1) {
> +	while (pci_read_vpd_any(dev, off, 1, header) == 1) {
>   		size = 0;
>   
>   		if (off == 0 && (header[0] == 0x00 || header[0] == 0xff))
> @@ -68,7 +65,7 @@ static size_t pci_vpd_size(struct pci_dev *dev)
>   
>   		if (header[0] & PCI_VPD_LRDT) {
>   			/* Large Resource Data Type Tag */
> -			if (pci_read_vpd(dev, off + 1, 2, &header[1]) != 2) {
> +			if (pci_read_vpd_any(dev, off + 1, 2, &header[1]) != 2) {
>   				pci_warn(dev, "failed VPD read at offset %zu\n",
>   					 off + 1);
>   				return off ?: PCI_VPD_SZ_INVALID;
> 


This change is breaking a PCI test that we are running on Tegra124
Jetson TK1. The test is parsing the various PCI devices by running
'lspci -vvv' and for one device I am seeing a NULL pointer
dereference crash. Reverting this change or just adding the line
'dev->vpd.len = PCI_VPD_MAX_SIZE;' back fixes the problem.

I have taken a quick look but have not found why this is failing
so far. Let me know if you have any thoughts.

Cheers
Jon

[   56.577644] 8<--- cut here ---
[   56.580714] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   56.588836] pgd = da85f9ea
[   56.591545] [00000000] *pgd=00000000
[   56.595124] Internal error: Oops: 80000005 [#1] PREEMPT SMP ARM
[   56.601029] Modules linked in: nouveau drm_ttm_helper ttm tegra_soctherm
[   56.607725] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.15.0-rc2-00004-g7724d929fdde-dirty #5
[   56.616231] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
[   56.622482] PC is at 0x0
[   56.625007] LR is at rcu_core+0x368/0xc5c
[   56.629011] pc : [<00000000>]    lr : [<c01a3384>]    psr: 60000113
[   56.635261] sp : c1201dc8  ip : c35f4b80  fp : c1201df0
[   56.640472] r10: ffffe000  r9 : 00000007  r8 : c135d3a0
[   56.645683] r7 : 0000000a  r6 : c1204f0c  r5 : 00000008  r4 : 00000000
[   56.652193] r3 : c3c33850  r2 : 00000000  r1 : 00000000  r0 : c3c33850
[   56.658703] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[   56.665821] Control: 10c5387d  Table: 82e0806a  DAC: 00000051
[   56.671551] Register r0 information: slab kmalloc-64 start c3c33840 pointer offset 16 size 64
[   56.680066] Register r1 information: NULL pointer
[   56.684759] Register r2 information: NULL pointer
[   56.689451] Register r3 information: slab kmalloc-64 start c3c33840 pointer offset 16 size 64
[   56.697964] Register r4 information: NULL pointer
[   56.702655] Register r5 information: non-paged memory
[   56.707693] Register r6 information: non-slab/vmalloc memory
[   56.713338] Register r7 information: non-paged memory
[   56.718375] Register r8 information: non-slab/vmalloc memory
[   56.724020] Register r9 information: non-paged memory
[   56.729057] Register r10 information: non-paged memory
[   56.734183] Register r11 information: non-slab/vmalloc memory
[   56.739914] Register r12 information: slab kmalloc-64 start c35f4b80 pointer offset 0 size 64
[   56.748428] Process swapper/0 (pid: 0, stack limit = 0x54fa894a)
[   56.754419] Stack: (0xc1201dc8 to 0xc1202000)
[   56.758762] 1dc0:                   ???????? ???????? ???????? ???????? ???????? ????????
[   56.766919] 1de0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.775076] 1e00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.783232] 1e20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.791389] 1e40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.799545] 1e60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.807701] 1e80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.815857] 1ea0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.824014] 1ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.832170] 1ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.840326] 1f00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.848482] 1f20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.856639] 1f40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.864795] 1f60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.872951] 1f80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.881108] 1fa0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.889264] 1fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.897420] 1fe0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.905580] [<c01a3384>] (rcu_core) from [<c0101358>] (__do_softirq+0x130/0x42c)
[   56.912966] [<c0101358>] (__do_softirq) from [<c012bcec>] (irq_exit+0xbc/0x100)
[   56.920262] [<c012bcec>] (irq_exit) from [<c0189388>] (handle_domain_irq+0x60/0x78)
[   56.927906] [<c0189388>] (handle_domain_irq) from [<c051445c>] (gic_handle_irq+0x7c/0x90)
[   56.936071] [<c051445c>] (gic_handle_irq) from [<c0100b7c>] (__irq_svc+0x5c/0x90)
[   56.943538] Exception stack(0xc1201ec0 to 0xc1201f08)
[   56.948574] 1ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.956731] 1ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   56.964888] 1f00: ???????? ????????
[   56.968364] [<c0100b7c>] (__irq_svc) from [<c0865fb8>] (cpuidle_enter_state+0x258/0x4c0)
[   56.976441] [<c0865fb8>] (cpuidle_enter_state) from [<c0866270>] (cpuidle_enter+0x3c/0x54)
[   56.984687] [<c0866270>] (cpuidle_enter) from [<c015c568>] (do_idle+0x200/0x27c)
[   56.992069] [<c015c568>] (do_idle) from [<c015c93c>] (cpu_startup_entry+0x18/0x1c)
[   56.999623] [<c015c93c>] (cpu_startup_entry) from [<c1100fa8>] (start_kernel+0x664/0x6b0)
[   57.007786] Code: bad PC value
[   57.010968] 8<--- cut here ---

-- 
nvpublic