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JP Kobryn 764c6790dd 9p: prevent read overrun in protocol dump tracepoint 
commit a931c68160 upstream.

An out of bounds read can occur within the tracepoint 9p_protocol_dump. In
the fast assign, there is a memcpy that uses a constant size of 32 (macro
named P9_PROTO_DUMP_SZ). When the copy is invoked, the source buffer is not
guaranteed match this size.  It was found that in some cases the source
buffer size is less than 32, resulting in a read that overruns.

The size of the source buffer seems to be known at the time of the
tracepoint being invoked. The allocations happen within p9_fcall_init(),
where the capacity field is set to the allocated size of the payload
buffer. This patch tries to fix the overrun by changing the fixed array to
a dynamically sized array and using the minimum of the capacity value or
P9_PROTO_DUMP_SZ as its length. The trace log statement is adjusted to
account for this. Note that the trace log no longer splits the payload on
the first 16 bytes. The full payload is now logged to a single line.

To repro the orignal problem, operations to a plan 9 managed resource can
be used. The simplest approach might just be mounting a shared filesystem
(between host and guest vm) using the plan 9 protocol while the tracepoint
is enabled.

mount -t 9p -o trans=virtio <mount_tag> <mount_path>

The bpftrace program below can be used to show the out of bounds read.
Note that a recent version of bpftrace is needed for the raw tracepoint
support. The script was tested using v0.19.0.

/* from include/net/9p/9p.h */
struct p9_fcall {
    u32 size;
    u8 id;
    u16 tag;
    size_t offset;
    size_t capacity;
    struct kmem_cache *cache;
    u8 *sdata;
    bool zc;
};

tracepoint:9p:9p_protocol_dump
{
    /* out of bounds read can happen when this tracepoint is enabled */
}

rawtracepoint:9p_protocol_dump
{
    $pdu = (struct p9_fcall *)arg1;
    $dump_sz = (uint64)32;

    if ($dump_sz > $pdu->capacity) {
        printf("reading %zu bytes from src buffer of %zu bytes\n",
            $dump_sz, $pdu->capacity);
    }
}

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Message-ID: <20231204202321.22730-1-inwardvessel@gmail.com>
Fixes: 60ece0833b ("net/9p: allocate appropriate reduced message buffers")
Cc: stable@vger.kernel.org
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-01-01 12:39:05 +00:00
arch x86/xen: add CPU dependencies for 32-bit build 2024-01-01 12:38:59 +00:00
block blk-cgroup: bypass blkcg_deactivate_policy after destroying 2023-12-20 17:00:21 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:06:58 +00:00
Documentation dt-bindings: nvmem: mxs-ocotp: Document fsl,ocotp 2024-01-01 12:39:04 +00:00
drivers drm/i915: Reject async flips with bigjoiner 2024-01-01 12:39:05 +00:00
fs smb: client: fix OOB in smbCalcSize() 2024-01-01 12:39:05 +00:00
include 9p: prevent read overrun in protocol dump tracepoint 2024-01-01 12:39:05 +00:00
init proc: sysctl: prevent aliased sysctls from getting passed to init 2023-11-28 17:07:08 +00:00
io_uring io_uring: fix mutex_unlock with unreferenced ctx 2023-12-13 18:39:18 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Fix prog_array_map_poke_run map poke update 2024-01-01 12:38:52 +00:00
lib zstd: Fix array-index-out-of-bounds UBSAN warning 2023-12-13 18:39:04 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm kasan: disable kasan_non_canonical_hook() for HW tags 2024-01-01 12:38:52 +00:00
net net: rfkill: gpio: set GPIO direction 2024-01-01 12:39:04 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts sign-file: Fix incorrect return values check 2023-12-20 17:00:19 +01:00
security keys, dns: Allow key types (eg. DNS) to be reclaimed immediately on expiry 2024-01-01 12:38:58 +00:00
sound ALSA: hda/realtek: Add quirk for ASUS ROG GV302XA 2024-01-01 12:39:02 +00:00
tools selftests/bpf: fix bpf_loop_bench for new callback verification scheme 2023-12-20 17:00:23 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.69 2023-12-20 17:00:29 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.