Re: [PATCH v2] infiniband: remove WARN that is not kernel bug

[Leon Romanovsky]

On Mon, Nov 21, 2016 at 11:30:21AM +0100, Dmitry Vyukov wrote:
> On Mon, Nov 21, 2016 at 11:25 AM, Miroslav Benes <mbenes@xxxxxxx> wrote:
> > On Mon, 21 Nov 2016, Dmitry Vyukov wrote:
> >
> >> WARNINGs mean kernel bugs.
> >> The one in ucma_write() points to user programming error
> >> or a malicious attempt. This is not a kernel bug, remove it.
> >>
> >> BUG/WARNs that are not kernel bugs hinder automated testing effots.
> >>
> >> Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> >> Cc: Doug Ledford <dledford@xxxxxxxxxx>
> >> Cc: Sean Hefty <sean.hefty@xxxxxxxxx>
> >> Cc: Hal Rosenstock <hal.rosenstock@xxxxxxxxx>
> >> Cc: Leon Romanovsky <leon@xxxxxxxxxx>
> >> Cc: linux-rdma@xxxxxxxxxxxxxxx
> >> Cc: linux-kernel@xxxxxxxxxxxxxxx
> >> Cc: syzkaller@xxxxxxxxxxxxxxxx
> >>
> >> ---
> >> Changes since v1:
> >>  - added printk_once
> >> ---
> >>  drivers/infiniband/core/ucma.c | 5 ++++-
> >>  1 file changed, 4 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> >> index 9520154..405d0ce 100644
> >> --- a/drivers/infiniband/core/ucma.c
> >> +++ b/drivers/infiniband/core/ucma.c
> >> @@ -1584,8 +1584,11 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
> >>       struct rdma_ucm_cmd_hdr hdr;
> >>       ssize_t ret;
> >>
> >> -     if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
> >> +     if (!ib_safe_file_access(filp)) {
> >> +             printk_once("ucma_write: process %d (%s) tried to do something hinky\n",
> >> +                     task_tgid_vnr(current), current->comm);
> >>               return -EACCES;
> >> +     }
> >>
> >>       if (len < sizeof(hdr))
> >>               return -EINVAL;
> >
> > FWIW, WARN_ON_ONCE came with commit e6bd18f57aad ("IB/security: Restrict
> > use of the write() interface"). Would it make sense to change the other
> > places as well?
>
>
> I guess so.
> Can I ask somebody of infiniband maintainers to take care of this?

Please see below,
Hope it helps.


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From e0bfe4771591f9ffbcaa4e66d6257ed95e2d7188 Mon Sep 17 00:00:00 2001
From: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Date: Mon, 21 Nov 2016 13:30:59 +0200
Subject: [PATCH] IB/{core, qib}: Remove WARN that is not kernel bug

WARNINGs mean kernel bugs, in this case, they are placed
to mark programming errors and/or malicious attempts.

BUG/WARNs that are not kernel bugs hinder automated testing efforts.

Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
---
 drivers/infiniband/core/ucm.c            | 5 ++++-
 drivers/infiniband/core/ucma.c           | 5 ++++-
 drivers/infiniband/core/uverbs_main.c    | 5 ++++-
 drivers/infiniband/hw/qib/qib_file_ops.c | 5 ++++-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index 7713ef0..0076b55 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -1104,8 +1104,11 @@ static ssize_t ib_ucm_write(struct file *filp, const char __user *buf,
 	struct ib_ucm_cmd_hdr hdr;
 	ssize_t result;

-	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+	if (!ib_safe_file_access(filp)) {
+		pr_err_once("ucm_write: process %d (%s) tried to do something hinky\n",
+			    task_tgid_vnr(current), current->comm);
 		return -EACCES;
+	}

 	if (len < sizeof(hdr))
 		return -EINVAL;
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 9520154..31fa27f 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1584,8 +1584,11 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
 	struct rdma_ucm_cmd_hdr hdr;
 	ssize_t ret;

-	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+	if (!ib_safe_file_access(filp)) {
+		pr_err_once("ucma_write: process %d (%s) tried to do something hinky\n",
+			    task_tgid_vnr(current), current->comm);
 		return -EACCES;
+	}

 	if (len < sizeof(hdr))
 		return -EINVAL;
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 44b1104..329eb15 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -746,8 +746,11 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
 	int srcu_key;
 	ssize_t ret;

-	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+	if (!ib_safe_file_access(filp)) {
+		pr_err_once("uverbs_write: process %d (%s) tried to do something hinky\n",
+			    task_tgid_vnr(current), current->comm);
 		return -EACCES;
+	}

 	if (count < sizeof hdr)
 		return -EINVAL;
diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c
index 382466a..b43ea52 100644
--- a/drivers/infiniband/hw/qib/qib_file_ops.c
+++ b/drivers/infiniband/hw/qib/qib_file_ops.c
@@ -2066,8 +2066,11 @@ static ssize_t qib_write(struct file *fp, const char __user *data,
 	ssize_t ret = 0;
 	void *dest;

-	if (WARN_ON_ONCE(!ib_safe_file_access(fp)))
+	if (!ib_safe_file_access(fp)) {
+		pr_err_once("qib_write: process %d (%s) tried to do something hinky\n",
+			    task_tgid_vnr(current), current->comm);
 		return -EACCES;
+	}

 	if (count < sizeof(cmd.type)) {
 		ret = -EINVAL;
--
2.7.4

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