On 3/15/24 00:06, Michael Chang via Grub-devel wrote:
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);
Why do you duplicate the string?
+ tmp = get_basename(directory);
+ curr_device = grub_strdup (tmp);
+ *tmp = '\0';
Is this necessary?
+
+ /* Recursively check for slaves devices so we can find the root device */
+ while ((curr_device[0] == 'd') && (curr_device[1] == 'm') && (curr_device[2]
== '-')){
grub_strncmp(curr_device, "dm-", 3) == 0 ?
+ 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;
if (!strcmp(ep->d_name, ".") || !(strcmp(ep->d_name, ".."))
{
ep = readdir(dp);
continue;
}
+
+ free (curr_device);
+ free (ret); >> + curr_device = grub_strdup (ep->d_name);>> + ret =
grub_xasprintf ("%s%s", directory, curr_device);
you will still have to test for NULL pointers after grub_strdup() and
grub_xasprintf() calls.
+ 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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