On Mon, May 08, 2023 at 01:58:36PM +0000, Avnish Chouhan wrote:
> From: Diego Domingos <dieg...@br.ibm.com>
>
> This patch enables the device mapper discovery on ofpath.c. Currently,
> when we are dealing with a device like /dev/dm-* the ofpath returns null
> since there is no function implemented to handle this case.
>
> This patch implements a function that will look into /sys/block/dm-*
> devices and search recursively inside slaves directory to find the root
> disk.
>
> Signed-off-by: Diego Domingos <dieg...@br.ibm.com>
> ---
> grub-core/osdep/linux/ofpath.c | 64 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
> index 0f5d54e9f2d..cc849d9c94c 100644
> --- a/grub-core/osdep/linux/ofpath.c
> +++ b/grub-core/osdep/linux/ofpath.c
> @@ -37,6 +37,7 @@
> #include <fcntl.h>
> #include <errno.h>
> #include <ctype.h>
> +#include <dirent.h>
>
> #ifdef __sparc__
> typedef enum
> @@ -755,13 +756,74 @@ strip_trailing_digits (const char *p)
> return new;
> }
>
> +static char *
> +get_slave_from_dm(const char * device){
> + char *curr_device, *tmp;
> + char *directory;
> + char *ret = NULL;
> +
> + directory = grub_strdup (device);
> + tmp = get_basename(directory);
> + curr_device = grub_strdup (tmp);
> + *tmp = '\0';
> +
> + /* Recursively check for slaves devices so we can find the root device */
> + while ((curr_device[0] == 'd') && (curr_device[1] == 'm') &&
> (curr_device[2] == '-')){
> + DIR *dp;
> + struct dirent *ep;
> + char* device_path;
> +
> + device_path = grub_xasprintf ("/sys/block/%s/slaves", curr_device);
> + dp = opendir(device_path);
> + free(device_path);
> +
> + if (dp != NULL)
> + {
> + ep = readdir (dp);
> + while (ep != NULL)
> + {
> + /* avoid some system directories */
> + if (!strcmp(ep->d_name,"."))
> + goto next_dir;
> + if (!strcmp(ep->d_name,".."))
> + goto next_dir;
> +
> + free (curr_device);
> + free (ret);
> + curr_device = grub_strdup (ep->d_name);
> + ret = grub_xasprintf ("%s%s", directory, curr_device);
> + break;
> +
> + next_dir:
> + ep = readdir (dp);
> + continue;
> + }
> + closedir (dp);
> + }
> + else
> + grub_util_warn (_("cannot open directory `%s'"), device_path);
This will lead to UAF (Use After Free) for the device_path pointer.
Thanks,
Micahel
> + }
> +
> + free (directory);
> + free (curr_device);
> +
> + return ret;
> +}
> +
> char *
> grub_util_devname_to_ofpath (const char *sys_devname)
> {
> - char *name_buf, *device, *devnode, *devicenode, *ofpath;
> + char *name_buf, *device, *devnode, *devicenode, *ofpath, *realname;
>
> name_buf = xrealpath (sys_devname);
>
> + realname = get_slave_from_dm (name_buf);
> + if (realname)
> + {
> + free (name_buf);
> + name_buf = realname;
> + }
> +
> device = get_basename (name_buf);
> devnode = strip_trailing_digits (name_buf);
> devicenode = strip_trailing_digits (device);
>
> _______________________________________________
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