Re: [PATCH 2/4] kunit: Fix possible null-ptr-deref in kunit_parse_glob_filter()

From: Rae Moar <rmoar@google.com>
To: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: brendan.higgins@linux.dev, davidgow@google.com,
	skhan@linuxfoundation.org, jk@codeconstruct.com.au,
	dlatypov@google.com, linux-kselftest@vger.kernel.org,
	kunit-dev@googlegroups.com
Subject: Re: [PATCH 2/4] kunit: Fix possible null-ptr-deref in kunit_parse_glob_filter()
Date: Thu, 31 Aug 2023 16:34:03 -0400	[thread overview]
Message-ID: <CA+GJov4sxNxNF0-ERMizaNaXyb7Q_gq5n74gbGj2BuC+g8Pw4w@mail.gmail.com> (raw)
In-Reply-To: <20230831071655.2907683-3-ruanjinjie@huawei.com>

On Thu, Aug 31, 2023 at 3:17 AM 'Jinjie Ruan' via KUnit Development
<kunit-dev@googlegroups.com> wrote:
>
> Inject fault while probing kunit-example-test.ko, if kzalloc fails
> in kunit_parse_glob_filter(), strcpy() or strncpy() to NULL will
> cause below null-ptr-deref bug. So check NULL for kzalloc() and
> return int instead of void for kunit_parse_glob_filter().
>
>  Unable to handle kernel paging request at virtual address dfff800000000000
>  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
>  Mem abort info:
>    ESR = 0x0000000096000005
>    EC = 0x25: DABT (current EL), IL = 32 bits
>    SET = 0, FnV = 0
>    EA = 0, S1PTW = 0
>    FSC = 0x05: level 1 translation fault
>  Data abort info:
>    ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
>    CM = 0, WnR = 0, TnD = 0, TagAccess = 0
>    GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
>  [dfff800000000000] address between user and kernel address ranges
>  Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
>  Modules linked in: kunit_example_test cfg80211 rfkill 8021q garp mrp stp llc ipv6 [last unloaded: kunit_example_test]
>  CPU: 4 PID: 6047 Comm: modprobe Tainted: G        W        N 6.5.0-next-20230829+ #141
>  Hardware name: linux,dummy-virt (DT)
>  pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>  pc : strncpy+0x58/0xc0
>  lr : kunit_filter_suites+0x15c/0xa84
>  sp : ffff800082a17420
>  x29: ffff800082a17420 x28: 0000000000000000 x27: 0000000000000004
>  x26: 0000000000000000 x25: ffffa847e40a5320 x24: 0000000000000001
>  x23: 0000000000000000 x22: 0000000000000001 x21: dfff800000000000
>  x20: 000000000000002a x19: 0000000000000000 x18: 00000000750b3b54
>  x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
>  x14: 0000000000000000 x13: 34393178302f3039 x12: ffff7508fcea4ec1
>  x11: 1ffff508fcea4ec0 x10: ffff7508fcea4ec0 x9 : dfff800000000000
>  x8 : ffff6051b1a7f86a x7 : ffff800082a17270 x6 : 0000000000000002
>  x5 : 0000000000000098 x4 : ffff028d9817b250 x3 : 0000000000000000
>  x2 : 0000000000000000 x1 : ffffa847e40a5320 x0 : 0000000000000000
>  Call trace:
>   strncpy+0x58/0xc0
>   kunit_filter_suites+0x15c/0xa84
>   kunit_module_notify+0x1b0/0x3ac
>   blocking_notifier_call_chain+0xc4/0x128
>   do_init_module+0x250/0x594
>   load_module+0x37b0/0x44b4
>   init_module_from_file+0xd4/0x128
>   idempotent_init_module+0x2c8/0x524
>   __arm64_sys_finit_module+0xac/0x100
>   invoke_syscall+0x6c/0x258
>   el0_svc_common.constprop.0+0x160/0x22c
>   do_el0_svc+0x44/0x5c
>   el0_svc+0x38/0x78
>   el0t_64_sync_handler+0x13c/0x158
>   el0t_64_sync+0x190/0x194
>  Code: 5400028a d343fe63 12000a62 39400034 (38f56863)
>  ---[ end trace 0000000000000000 ]---
>  Kernel panic - not syncing: Oops: Fatal exception
>  SMP: stopping secondary CPUs
>  Kernel Offset: 0x284761400000 from 0xffff800080000000
>  PHYS_OFFSET: 0xfffffd7380000000
>  CPU features: 0x88000203,3c020000,1000421b
>  Memory Limit: none
>  Rebooting in 1 seconds..
>
> Fixes: a127b154a8f2 ("kunit: tool: allow filtering test cases via glob")
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>

Hello!

This also looks good to me. Thanks for catching these!

Reviewed-by: Rae Moar <rmoar@google.com>

Thanks!
-Rae

> ---
>  lib/kunit/executor.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
> index 5181aa2e760b..25ce8d6e5fe7 100644
> --- a/lib/kunit/executor.c
> +++ b/lib/kunit/executor.c
> @@ -65,7 +65,7 @@ struct kunit_glob_filter {
>  };
>
>  /* Split "suite_glob.test_glob" into two. Assumes filter_glob is not empty. */
> -static void kunit_parse_glob_filter(struct kunit_glob_filter *parsed,
> +static int kunit_parse_glob_filter(struct kunit_glob_filter *parsed,
>                                     const char *filter_glob)
>  {
>         const int len = strlen(filter_glob);
> @@ -73,16 +73,28 @@ static void kunit_parse_glob_filter(struct kunit_glob_filter *parsed,
>
>         if (!period) {
>                 parsed->suite_glob = kzalloc(len + 1, GFP_KERNEL);
> +               if (!parsed->suite_glob)
> +                       return -ENOMEM;
> +
>                 parsed->test_glob = NULL;
>                 strcpy(parsed->suite_glob, filter_glob);
> -               return;
> +               return 0;
>         }
>
>         parsed->suite_glob = kzalloc(period - filter_glob + 1, GFP_KERNEL);
> +       if (!parsed->suite_glob)
> +               return -ENOMEM;
> +
>         parsed->test_glob = kzalloc(len - (period - filter_glob) + 1, GFP_KERNEL);
> +       if (!parsed->test_glob) {
> +               kfree(parsed->suite_glob);
> +               return -ENOMEM;
> +       }
>
>         strncpy(parsed->suite_glob, filter_glob, period - filter_glob);
>         strncpy(parsed->test_glob, period + 1, len - (period - filter_glob));
> +
> +       return 0;
>  }
>
>  /* Create a copy of suite with only tests that match test_glob. */
> @@ -152,8 +164,13 @@ kunit_filter_suites(const struct kunit_suite_set *suite_set,
>         }
>         copy_start = copy;
>
> -       if (filter_glob)
> -               kunit_parse_glob_filter(&parsed_glob, filter_glob);
> +       if (filter_glob) {
> +               *err = kunit_parse_glob_filter(&parsed_glob, filter_glob);
> +               if (*err) {
> +                       kfree(copy);
> +                       return filtered;
> +               }
> +       }
>
>         /* Parse attribute filters */
>         if (filters) {
> --
> 2.34.1
>
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