[LTP] [PATCH 1/2] ioctl_sg01: Allow using USB device again

[Cyril Hrubis]

Hi!
> The failures when the ioctl_sg01 test tried to query a USB device
> turned out to be another data leak. Allow using USB devices again
> but keep the improved device lookup algorithm.
> 
> Signed-off-by: Martin Doucha <mdoucha@suse.cz>
> ---
> 
> Tested on kernels v4.4 and v6.12.
> 
>  testcases/kernel/syscalls/ioctl/ioctl_sg01.c | 29 ++++++--------------
>  1 file changed, 8 insertions(+), 21 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/ioctl/ioctl_sg01.c b/testcases/kernel/syscalls/ioctl/ioctl_sg01.c
> index dada174e0..9862d7324 100644
> --- a/testcases/kernel/syscalls/ioctl/ioctl_sg01.c
> +++ b/testcases/kernel/syscalls/ioctl/ioctl_sg01.c
> @@ -30,7 +30,7 @@
>  #include "tst_memutils.h"
>  
>  #define SYSDIR "/sys/block"
> -#define BLOCKDIR "/sys/block/%s/device"
> +#define BLOCKDIR "/sys/block/%s/device/generic"
>  
>  #define BUF_SIZE (128 * 4096)
>  #define CMD_SIZE 6
> @@ -41,14 +41,14 @@ static unsigned char command[CMD_SIZE];
>  static struct sg_io_hdr query;
>  
>  /* TODO: split this off to a separate SCSI library? */
> -static const char *find_generic_scsi_device(int access_flags, int skip_usb)
> +static const char *find_generic_scsi_device(int access_flags)
>  {
>  	DIR *sysdir;
>  	struct dirent *ent;
>  	int tmpfd;
>  	ssize_t length;
>  	char *filename;
> -	static char devpath[PATH_MAX], syspath[PATH_MAX];
> +	static char devpath[PATH_MAX], genpath[PATH_MAX];
>  
>  	sysdir = opendir(SYSDIR);
>  
> @@ -60,28 +60,15 @@ static const char *find_generic_scsi_device(int access_flags, int skip_usb)
>  		if (ent->d_name[0] == '.')
>  			continue;
>  
> -		snprintf(syspath, PATH_MAX, BLOCKDIR, ent->d_name);
> -		syspath[PATH_MAX - 1] = '\0';
> -
> -		/* Real device path matches the physical HW bus path */
> -		if (!realpath(syspath, devpath))
> -			continue;
> -
> -		strncat(devpath, "/generic", PATH_MAX - strlen(devpath) - 1);
> +		snprintf(devpath, PATH_MAX, BLOCKDIR, ent->d_name);
>  		devpath[PATH_MAX - 1] = '\0';
> -		length = readlink(devpath, syspath, PATH_MAX - 1);
> +		length = readlink(devpath, genpath, PATH_MAX - 1);
>  
>  		if (length < 0)
>  			continue;
>  
> -		syspath[length] = '\0';
> -		filename = basename(syspath);
> -
> -		/* USB devices often return HW info in SG_IO response buffer */
> -		if (skip_usb && strstr(devpath, "/usb")) {
> -			tst_res(TINFO, "Skipping USB device %s", filename);
> -			continue;
> -		}
> +		genpath[length] = '\0';
> +		filename = basename(genpath);
>  
>  		snprintf(devpath, PATH_MAX, "/dev/%s", filename);
>  		/* access() makes incorrect assumptions about block devices */
> @@ -121,7 +108,7 @@ static void dump_hex(const char *str, size_t size)

I just wonder, shouldn't we find all the devices on the system and
return array of strings? Or at least pick at least one device per
differet bus?

-- 
Cyril Hrubis
chrubis@suse.cz