6.6-stable review patch. If anyone has any objections, please let me know.
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From: Roman Gushchin roman.gushchin@linux.dev
[ Upstream commit a1ecb30f90856b0be4168ad51b8875148e285c1f ]
Commit 467f432a521a ("RDMA/core: Split port and device counter sysfs attributes") accidentally almost exposed hw counters to non-init net namespaces. It didn't expose them fully, as an attempt to read any of those counters leads to a crash like this one:
[42021.807566] BUG: kernel NULL pointer dereference, address: 0000000000000028 [42021.814463] #PF: supervisor read access in kernel mode [42021.819549] #PF: error_code(0x0000) - not-present page [42021.824636] PGD 0 P4D 0 [42021.827145] Oops: 0000 [#1] SMP PTI [42021.830598] CPU: 82 PID: 2843922 Comm: switchto-defaul Kdump: loaded Tainted: G S W I XXX [42021.841697] Hardware name: XXX [42021.849619] RIP: 0010:hw_stat_device_show+0x1e/0x40 [ib_core] [42021.855362] Code: 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 49 89 d0 4c 8b 5e 20 48 8b 8f b8 04 00 00 48 81 c7 f0 fa ff ff <48> 8b 41 28 48 29 ce 48 83 c6 d0 48 c1 ee 04 69 d6 ab aa aa aa 48 [42021.873931] RSP: 0018:ffff97fe90f03da0 EFLAGS: 00010287 [42021.879108] RAX: ffff9406988a8c60 RBX: ffff940e1072d438 RCX: 0000000000000000 [42021.886169] RDX: ffff94085f1aa000 RSI: ffff93c6cbbdbcb0 RDI: ffff940c7517aef0 [42021.893230] RBP: ffff97fe90f03e70 R08: ffff94085f1aa000 R09: 0000000000000000 [42021.900294] R10: ffff94085f1aa000 R11: ffffffffc0775680 R12: ffffffff87ca2530 [42021.907355] R13: ffff940651602840 R14: ffff93c6cbbdbcb0 R15: ffff94085f1aa000 [42021.914418] FS: 00007fda1a3b9700(0000) GS:ffff94453fb80000(0000) knlGS:0000000000000000 [42021.922423] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [42021.928130] CR2: 0000000000000028 CR3: 00000042dcfb8003 CR4: 00000000003726f0 [42021.935194] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [42021.942257] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [42021.949324] Call Trace: [42021.951756] <TASK> [42021.953842] [<ffffffff86c58674>] ? show_regs+0x64/0x70 [42021.959030] [<ffffffff86c58468>] ? __die+0x78/0xc0 [42021.963874] [<ffffffff86c9ef75>] ? page_fault_oops+0x2b5/0x3b0 [42021.969749] [<ffffffff87674b92>] ? exc_page_fault+0x1a2/0x3c0 [42021.975549] [<ffffffff87801326>] ? asm_exc_page_fault+0x26/0x30 [42021.981517] [<ffffffffc0775680>] ? __pfx_show_hw_stats+0x10/0x10 [ib_core] [42021.988482] [<ffffffffc077564e>] ? hw_stat_device_show+0x1e/0x40 [ib_core] [42021.995438] [<ffffffff86ac7f8e>] dev_attr_show+0x1e/0x50 [42022.000803] [<ffffffff86a3eeb1>] sysfs_kf_seq_show+0x81/0xe0 [42022.006508] [<ffffffff86a11134>] seq_read_iter+0xf4/0x410 [42022.011954] [<ffffffff869f4b2e>] vfs_read+0x16e/0x2f0 [42022.017058] [<ffffffff869f50ee>] ksys_read+0x6e/0xe0 [42022.022073] [<ffffffff8766f1ca>] do_syscall_64+0x6a/0xa0 [42022.027441] [<ffffffff8780013b>] entry_SYSCALL_64_after_hwframe+0x78/0xe2
The problem can be reproduced using the following steps: ip netns add foo ip netns exec foo bash cat /sys/class/infiniband/mlx4_0/hw_counters/*
The panic occurs because of casting the device pointer into an ib_device pointer using container_of() in hw_stat_device_show() is wrong and leads to a memory corruption.
However the real problem is that hw counters should never been exposed outside of the non-init net namespace.
Fix this by saving the index of the corresponding attribute group (it might be 1 or 2 depending on the presence of driver-specific attributes) and zeroing the pointer to hw_counters group for compat devices during the initialization.
With this fix applied hw_counters are not available in a non-init net namespace: find /sys/class/infiniband/mlx4_0/ -name hw_counters /sys/class/infiniband/mlx4_0/ports/1/hw_counters /sys/class/infiniband/mlx4_0/ports/2/hw_counters /sys/class/infiniband/mlx4_0/hw_counters
ip netns add foo ip netns exec foo bash find /sys/class/infiniband/mlx4_0/ -name hw_counters
Fixes: 467f432a521a ("RDMA/core: Split port and device counter sysfs attributes") Signed-off-by: Roman Gushchin roman.gushchin@linux.dev Cc: Jason Gunthorpe jgg@ziepe.ca Cc: Leon Romanovsky leon@kernel.org Cc: Maher Sanalla msanalla@nvidia.com Cc: linux-rdma@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: https://patch.msgid.link/20250227165420.3430301-1-roman.gushchin@linux.dev Reviewed-by: Parav Pandit parav@nvidia.com Signed-off-by: Leon Romanovsky leon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/device.c | 9 +++++++++ drivers/infiniband/core/sysfs.c | 1 + include/rdma/ib_verbs.h | 1 + 3 files changed, 11 insertions(+)
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index 56dd030045a20..6769c42e46d4f 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -543,6 +543,8 @@ static struct class ib_class = { static void rdma_init_coredev(struct ib_core_device *coredev, struct ib_device *dev, struct net *net) { + bool is_full_dev = &dev->coredev == coredev; + /* This BUILD_BUG_ON is intended to catch layout change * of union of ib_core_device and device. * dev must be the first element as ib_core and providers @@ -554,6 +556,13 @@ static void rdma_init_coredev(struct ib_core_device *coredev,
coredev->dev.class = &ib_class; coredev->dev.groups = dev->groups; + + /* + * Don't expose hw counters outside of the init namespace. + */ + if (!is_full_dev && dev->hw_stats_attr_index) + coredev->dev.groups[dev->hw_stats_attr_index] = NULL; + device_initialize(&coredev->dev); coredev->owner = dev; INIT_LIST_HEAD(&coredev->port_list); diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c index 9f97bef021497..210092b9bf17d 100644 --- a/drivers/infiniband/core/sysfs.c +++ b/drivers/infiniband/core/sysfs.c @@ -988,6 +988,7 @@ int ib_setup_device_attrs(struct ib_device *ibdev) for (i = 0; i != ARRAY_SIZE(ibdev->groups); i++) if (!ibdev->groups[i]) { ibdev->groups[i] = &data->group; + ibdev->hw_stats_attr_index = i; return 0; } WARN(true, "struct ib_device->groups is too small"); diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index bc459d0616297..c7e9ec9e9a802 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -2738,6 +2738,7 @@ struct ib_device { * It is a NULL terminated array. */ const struct attribute_group *groups[4]; + u8 hw_stats_attr_index;
u64 uverbs_cmd_mask;