2022-11-02 09:24:08

by Pu Lehui

Subject: [PATCH bpf] bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE

From: Pu Lehui <[email protected]>

When using bpftool to pin {PROG, MAP, LINK} without FILE,
segmentation fault will occur. The reson is that the lack
of FILE will cause strlen to trigger NULL pointer dereference.
The corresponding stacktrace is shown below:

do_pin
do_pin_any
do_pin_fd
mount_bpffs_for_pin
strlen(name) <- NULL pointer dereference

Fix it by adding validation to the common process.

Fixes: 75a1e792c335 ("tools: bpftool: Allow all prog/map handles for pinning objects")
Signed-off-by: Pu Lehui <[email protected]>
---
tools/bpf/bpftool/common.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index e4d33bc8bbbf..653c130a0aaa 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -302,6 +302,9 @@ int do_pin_any(int argc, char **argv, int (*get_fd)(int *, char ***))
int err;
int fd;

+ if (!REQ_ARGS(3))
+ return -EINVAL;
+
fd = get_fd(&argc, &argv);
if (fd < 0)
return fd;
--
2.25.1

2022-11-02 11:28:29

by Quentin Monnet

Subject: Re: [PATCH bpf] bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE

2022-11-02 16:40 UTC+0800 ~ Pu Lehui <[email protected]>
> From: Pu Lehui <[email protected]>
>
> When using bpftool to pin {PROG, MAP, LINK} without FILE,
> segmentation fault will occur. The reson is that the lack
> of FILE will cause strlen to trigger NULL pointer dereference.
> The corresponding stacktrace is shown below:
>
> do_pin
> do_pin_any
> do_pin_fd
> mount_bpffs_for_pin
> strlen(name) <- NULL pointer dereference
>
> Fix it by adding validation to the common process.
>
> Fixes: 75a1e792c335 ("tools: bpftool: Allow all prog/map handles for pinning objects")
> Signed-off-by: Pu Lehui <[email protected]>
> ---
> tools/bpf/bpftool/common.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
> index e4d33bc8bbbf..653c130a0aaa 100644
> --- a/tools/bpf/bpftool/common.c
> +++ b/tools/bpf/bpftool/common.c
> @@ -302,6 +302,9 @@ int do_pin_any(int argc, char **argv, int (*get_fd)(int *, char ***))
> int err;
> int fd;
>
> + if (!REQ_ARGS(3))
> + return -EINVAL;
> +
> fd = get_fd(&argc, &argv);
> if (fd < 0)
> return fd;

Good catch, and thanks for the fix!

Reviewed-by: Quentin Monnet <[email protected]>

2022-11-02 11:55:23

by patchwork-bot+netdevbpf

Subject: Re: [PATCH bpf] bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE

Hello:

This patch was applied to bpf/bpf.git (master)
by Daniel Borkmann <[email protected]>:

On Wed, 2 Nov 2022 16:40:34 +0800 you wrote:
> From: Pu Lehui <[email protected]>
>
> When using bpftool to pin {PROG, MAP, LINK} without FILE,
> segmentation fault will occur. The reson is that the lack
> of FILE will cause strlen to trigger NULL pointer dereference.
> The corresponding stacktrace is shown below:
>
> [...]

Here is the summary with links:
- [bpf] bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE
https://git.kernel.org/bpf/bpf/c/34de8e6e0e1f

You are awesome, thank you!
--
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