[PATCH 6.7 688/713] net/bnx2x: Prevent access to a freed page in page_pool

Sasha Levin
2024-03-24T22:58:47Z

From: Thinh Tran <thinhtr@linux.ibm.com>

[ Upstream commit d27e2da94a42655861ca4baea30c8cd65546f25d ]

Fix race condition leading to system crash during EEH error handling

During EEH error recovery, the bnx2x driver's transmit timeout logic
could cause a race condition when handling reset tasks. The
bnx2x_tx_timeout() schedules reset tasks via bnx2x_sp_rtnl_task(),
which ultimately leads to bnx2x_nic_unload(). In bnx2x_nic_unload()
SGEs are freed using bnx2x_free_rx_sge_range(). However, this could
overlap with the EEH driver's attempt to reset the device using
bnx2x_io_slot_reset(), which also tries to free SGEs. This race
condition can result in system crashes due to accessing freed memory
locations in bnx2x_free_rx_sge()

799 static inline void bnx2x_free_rx_sge(struct bnx2x *bp,
800 struct bnx2x_fastpath *fp, u16 index)
801 {
802 struct sw_rx_page *sw_buf = &fp->rx_page_ring[index];
803 struct page *page = sw_buf->page;
....
where sw_buf was set to NULL after the call to dma_unmap_page()
by the preceding thread.

EEH: Beginning: 'slot_reset'
PCI 0011:01:00.0#10000: EEH: Invoking bnx2x->slot_reset()
bnx2x: [bnx2x_io_slot_reset:14228(eth1)]IO slot reset initializing...
bnx2x 0011:01:00.0: enabling device (0140 -> 0142)
bnx2x: [bnx2x_io_slot_reset:14244(eth1)]IO slot reset --> driver unload
Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc0080000025065fc
Oops: Kernel access of bad area, sig: 11 [#1]
.....
Call Trace:
[c000000003c67a20] [c00800000250658c] bnx2x_io_slot_reset+0x204/0x610 [bnx2x] (unreliable)
[c000000003c67af0] [c0000000000518a8] eeh_report_reset+0xb8/0xf0
[c000000003c67b60] [c000000000052130] eeh_pe_report+0x180/0x550
[c000000003c67c70] [c00000000005318c] eeh_handle_normal_event+0x84c/0xa60
[c000000003c67d50] [c000000000053a84] eeh_event_handler+0xf4/0x170
[c000000003c67da0] [c000000000194c58] kthread+0x1c8/0x1d0
[c000000003c67e10] [c00000000000cf64] ret_from_kernel_thread+0x5c/0x64

To solve this issue, we need to verify page pool allocations before
freeing.

Fixes: 4cace675d687 ("bnx2x: Alloc 4k fragment for each rx ring buffer element")
Signed-off-by: Thinh Tran <thinhtr@linux.ibm.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240315205535.1321-1-thinhtr@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
index d8b1824c334d3..0bc1367fd6492 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
@@ -1002,9 +1002,6 @@ static inline void bnx2x_set_fw_mac_addr(__le16 *fw_hi, __le16 *fw_mid,
static inline void bnx2x_free_rx_mem_pool(struct bnx2x *bp,
struct bnx2x_alloc_pool *pool)
{
- if (!pool->page)
- return;
-
put_page(pool->page);

pool->page = NULL;
@@ -1015,6 +1012,9 @@ static inline void bnx2x_free_rx_sge_range(struct bnx2x *bp,
{
int i;

+ if (!fp->page_pool.page)
+ return;
+
if (fp->mode == TPA_MODE_DISABLED)
return;

--
2.43.0