| From 8d3ae59dee2930d640add3bba983006e1f5dd1b6 Mon Sep 17 00:00:00 2001 |
| From: Daniel Axtens <dja@axtens.net> |
| Date: Mon, 18 Jan 2021 14:34:58 +1100 |
| Subject: [PATCH] fs/sfs: Fix over-read of root object name |
| |
| There's a read of the name of the root object that assumes that the name |
| is nul-terminated within the root block. This isn't guaranteed - it seems |
| SFS would require you to read multiple blocks to get a full name in general, |
| but maybe that doesn't apply to the root object. |
| |
| Either way, figure out how much space is left in the root block and don't |
| over-read it. This fixes some OOB reads. |
| |
| Signed-off-by: Daniel Axtens <dja@axtens.net> |
| Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> |
| Signed-off-by: Stefan SΓΈrensen <stefan.sorensen@spectralink.com> |
| --- |
| grub-core/fs/sfs.c | 9 ++++++++- |
| 1 file changed, 8 insertions(+), 1 deletion(-) |
| |
| diff --git a/grub-core/fs/sfs.c b/grub-core/fs/sfs.c |
| index de2b107..983e880 100644 |
| --- a/grub-core/fs/sfs.c |
| +++ b/grub-core/fs/sfs.c |
| @@ -373,6 +373,7 @@ grub_sfs_mount (grub_disk_t disk) |
| struct grub_sfs_objc *rootobjc; |
| char *rootobjc_data = 0; |
| grub_uint32_t blk; |
| + unsigned int max_len; |
| |
| data = grub_malloc (sizeof (*data)); |
| if (!data) |
| @@ -421,7 +422,13 @@ grub_sfs_mount (grub_disk_t disk) |
| data->diropen.data = data; |
| data->diropen.cache = 0; |
| data->disk = disk; |
| - data->label = grub_strdup ((char *) (rootobjc->objects[0].filename)); |
| + |
| + /* We only read 1 block of data, so truncate the name if needed. */ |
| + max_len = ((GRUB_DISK_SECTOR_SIZE << data->log_blocksize) |
| + - 24 /* offsetof (struct grub_sfs_objc, objects) */ |
| + - 25); /* offsetof (struct grub_sfs_obj, filename) */ |
| + data->label = grub_zalloc (max_len + 1); |
| + grub_strncpy (data->label, (char *) rootobjc->objects[0].filename, max_len); |
| |
| grub_free (rootobjc_data); |
| return data; |
| -- |
| 2.14.2 |
| |