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From: Alexander Lobakin <aleksander.lobakin@intel.com>
To: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>
Cc: Alexander Lobakin <aleksander.lobakin@intel.com>,
	Michael Chan <michael.chan@broadcom.com>,
	Somnath Kotur <somnath.kotur@broadcom.com>,
	Pavan Chebbi <pavan.chebbi@broadcom.com>,
	Kalesh AP <kalesh-anakkur.purayil@broadcom.com>,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH net-next] bnxt_en: fix accessing vnic_info before allocating it
Date: Mon, 26 Feb 2024 15:49:11 +0100
Message-ID: <20240226144911.1297336-1-aleksander.lobakin@intel.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

bnxt_alloc_mem() dereferences ::vnic_info in the variable declaration
block, but allocates it much later. As a result, the following crash
happens on my setup:

 BUG: kernel NULL pointer dereference, address: 0000000000000090
 fbcon: Taking over console
 #PF: supervisor write access in kernel mode
 #PF: error_code (0x0002) - not-present page
 PGD 12f382067 P4D 0
 Oops: 8002 [#1] PREEMPT SMP NOPTI
 CPU: 47 PID: 2516 Comm: NetworkManager Not tainted 6.8.0-rc5-libeth+ #49
 Hardware name: Intel Corporation M50CYP2SBSTD/M58CYP2SBSTD, BIOS SE5C620.86B.01.01.0088.2305172341 05/17/2023
 RIP: 0010:bnxt_alloc_mem+0x1609/0x1910 [bnxt_en]
 Code: 81 c8 48 83 c8 08 31 c9 e9 d7 fe ff ff c7 44 24 Oc 00 00 00 00 49 89 d5 e9 2d fe ff ff 41 89 c6 e9 88 00 00 00 48 8b 44 24 50 <80> 88 90 00 00 00 Od 8b 43 74 a8 02 75 1e f6 83 14 02 00 00 80 74
 RSP: 0018:ff3f25580f3432c8 EFLAGS: 00010246
 RAX: 0000000000000000 RBX: ff15a5cfc45249e0 RCX: 0000002079777000
 RDX: ff15a5dfb9767000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
 R10: ff15a5dfb9777000 R11: ffffff8000000000 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000020 R15: ff15a5cfce34f540
 FS:  000007fb9a160500(0000) GS:ff15a5dfbefc0000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CRO: 0000000080050033
 CR2: 0000000000000090 CR3: 0000000109efc00Z CR4: 0000000000771ef0
 DR0: 0000000000000000 DR1: 0000000000000000 DRZ: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 PKRU: 55555554

 Call Trace:
 <TASK>
 ? __die_body+0x68/0xb0
 ? page_fault_oops+0x3a6/0x400
 ? exc_page_fault+0x7a/0x1b0
 ? asm_exc_page_fault+0x26/8x30
 ? bnxt_alloc_mem+0x1609/0x1910 [bnxt_en]
 ? bnxt_alloc_mem+0x1389/8x1918 [bnxt_en]
 _bnxt_open_nic+0x198/0xa50 [bnxt_en]
 ? bnxt_hurm_if_change+0x287/0x3d0 [bnxt_en]
 bnxt_open+0xeb/0x1b0 [bnxt_en]
 _dev_open+0x12e/0x1f0
 _dev_change_flags+0xb0/0x200
 dev_change_flags+0x25/0x60
 do_setlink+0x463/0x1260
 ? sock_def_readable+0x14/0xc0
 ? rtnl_getlink+0x4b9/0x590
 ? _nla_validate_parse+0x91/0xfa0
 rtnl_newlink+0xbac/0xe40
 <...>

Don't create a variable and dereference the first array member directly
since it's used only once in the code.

Fixes: ef4ee64e9990 ("bnxt_en: Define BNXT_VNIC_DEFAULT for the default vnic index")
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 9968d67e6c77..a15e6d31fc22 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -5004,7 +5004,6 @@ static void bnxt_free_mem(struct bnxt *bp, bool irq_re_init)
 
 static int bnxt_alloc_mem(struct bnxt *bp, bool irq_re_init)
 {
-	struct bnxt_vnic_info *vnic0 = &bp->vnic_info[BNXT_VNIC_DEFAULT];
 	int i, j, rc, size, arr_size;
 	void *bnapi;
 
@@ -5133,8 +5132,9 @@ static int bnxt_alloc_mem(struct bnxt *bp, bool irq_re_init)
 	if (rc)
 		goto alloc_mem_err;
 
-	vnic0->flags |= BNXT_VNIC_RSS_FLAG | BNXT_VNIC_MCAST_FLAG |
-			BNXT_VNIC_UCAST_FLAG;
+	bp->vnic_info[BNXT_VNIC_DEFAULT].flags |= BNXT_VNIC_RSS_FLAG |
+						  BNXT_VNIC_MCAST_FLAG |
+						  BNXT_VNIC_UCAST_FLAG;
 	if (BNXT_SUPPORTS_NTUPLE_VNIC(bp) && (bp->flags & BNXT_FLAG_RFS))
 		bp->vnic_info[BNXT_VNIC_NTUPLE].flags |=
 			BNXT_VNIC_RSS_FLAG | BNXT_VNIC_NTUPLE_FLAG;
-- 
2.43.2