Re: [PATCH 04/10] eal: fix plugin dir walk

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Jun 19, 2025 at 09:10:30AM +0200, David Marchand wrote:
> For '.' and '..' directories (or any short file name),
> a out of bound issue occurs.
> 
> Caught by UBSan:
> 
> EAL: Detected shared linkage of DPDK
> ../lib/eal/common/eal_common_options.c:420:15: runtime error: index -2
> 	out of bounds for type 'char[256]'
>     #0 0x7f867eedf206 in eal_plugindir_init
> 	eal_common_options.c
>     #1 0x7f867eede58a in eal_plugins_init
> 	(build/lib/librte_eal.so.25+0xde58a)
> 	(BuildId: e7e4a1935e4bacb51c82ab1a84098a27decf3b4c)
>     #2 0x7f867efb8587 in rte_eal_init
> 	(build/lib/librte_eal.so.25+0x1b8587)
> 	(BuildId: e7e4a1935e4bacb51c82ab1a84098a27decf3b4c)
>     #3 0x55b62360861e in main
> 	(/home/runner/work/dpdk/dpdk/build/app/dpdk-testpmd+0x9e061e)
> 	(BuildId: d821ec918612c83fad8b5ccb6cc518e66bee48cd)
>     #4 0x7f8667429d8f in __libc_start_call_main
> 	csu/../sysdeps/nptl/libc_start_call_main.h:58:16
>     #5 0x7f8667429e3f in __libc_start_main
> 	csu/../csu/libc-start.c:392:3
>     #6 0x55b622d9d444 in _start
> 	(/home/runner/work/dpdk/dpdk/build/app/dpdk-testpmd+0x175444)
> 	(BuildId: d821ec918612c83fad8b5ccb6cc518e66bee48cd)
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> 	../lib/eal/common/eal_common_options.c:420:15 in
> 	../lib/eal/common/eal_common_options.c:421:15:
> 	runtime error: index 18446744073709551609 out of bounds
> 	for type 'char[256]'
> 
> Fixes: c57f6e5c604a ("eal: fix plugin loading")
> Cc: stable@dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---
Acked-by: Bruce Richardson <bruce.richardson@intel.com>

One thought inline below...

>  lib/eal/common/eal_common_options.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/eal/common/eal_common_options.c b/lib/eal/common/eal_common_options.c
> index 83b6fc7e89..153f807e4f 100644
> --- a/lib/eal/common/eal_common_options.c
> +++ b/lib/eal/common/eal_common_options.c
> @@ -399,6 +399,14 @@ eal_plugins_init(void)
>  }
>  #else
>  
> +static bool
> +ends_with(const char *str, size_t str_len, const char *tail)
> +{
> +	size_t tail_len = strlen(tail);
> +
> +	return str_len >= tail_len && strncmp(&str[str_len - tail_len], tail, tail_len) == 0;
> +}
> +

I wonder if that function is worth renaming to "rte_str_ends_with" and
putting in rte_string_fns.h?


>  static int
>  eal_plugindir_init(const char *path)
>  {
> @@ -417,13 +425,12 @@ eal_plugindir_init(const char *path)
>  	}
>  
>  	while ((dent = readdir(d)) != NULL) {
> +		size_t nlen = strnlen(dent->d_name, sizeof(dent->d_name));
>  		struct stat sb;
> -		int nlen = strnlen(dent->d_name, sizeof(dent->d_name));
>  
>  		/* check if name ends in .so or .so.ABI_VERSION */
> -		if (strcmp(&dent->d_name[nlen - 3], ".so") != 0 &&
> -		    strcmp(&dent->d_name[nlen - 4 - strlen(ABI_VERSION)],
> -			   ".so."ABI_VERSION) != 0)
> +		if (!ends_with(dent->d_name, nlen, ".so") &&
> +				!ends_with(dent->d_name, nlen, ".so."ABI_VERSION))
>  			continue;
>  
>  		snprintf(sopath, sizeof(sopath), "%s/%s", path, dent->d_name);
> -- 
> 2.49.0
>