From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41517) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dTWl5-0004sX-A5 for qemu-devel@nongnu.org; Fri, 07 Jul 2017 13:09:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dTWl0-0007j3-Ty for qemu-devel@nongnu.org; Fri, 07 Jul 2017 13:09:35 -0400 From: Kevin Wolf Date: Fri, 7 Jul 2017 19:07:30 +0200 Message-Id: <1499447335-6125-16-git-send-email-kwolf@redhat.com> In-Reply-To: <1499447335-6125-1-git-send-email-kwolf@redhat.com> References: <1499447335-6125-1-git-send-email-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL 015/100] vvfat: limit number of entries in root directory in FAT12/FAT16 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Herv=C3=A9 Poussineau FAT12/FAT16 root directory is two sectors in size, which allows only 512 = directory entries. Prevent QEMU startup if too much files exist, instead of overflowing root= directory. Also introduce variable root_entries, which will be required for FAT32. Fixes: https://bugs.launchpad.net/qemu/+bug/1599539/comments/4 Signed-off-by: Herv=C3=A9 Poussineau Signed-off-by: Kevin Wolf --- block/vvfat.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/block/vvfat.c b/block/vvfat.c index 62f411b..dc9af01 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -337,8 +337,9 @@ typedef struct BDRVVVFATState { unsigned int cluster_size; unsigned int sectors_per_cluster; unsigned int sectors_per_fat; - unsigned int sectors_of_root_directory; uint32_t last_cluster_of_root_directory; + /* how many entries are available in root directory (0 for FAT32) */ + uint16_t root_entries; uint32_t sector_count; /* total number of sectors of the partition *= / uint32_t cluster_count; /* total number of clusters of this partitio= n */ uint32_t max_fat_value; @@ -785,6 +786,12 @@ static int read_directory(BDRVVVFATState* s, int map= ping_index) int is_dot=3D!strcmp(entry->d_name,"."); int is_dotdot=3D!strcmp(entry->d_name,".."); =20 + if (first_cluster =3D=3D 0 && s->directory.next >=3D s->root_ent= ries - 1) { + fprintf(stderr, "Too many entries in root directory\n"); + closedir(dir); + return -2; + } + if(first_cluster =3D=3D 0 && (is_dotdot || is_dot)) continue; =20 @@ -858,15 +865,15 @@ static int read_directory(BDRVVVFATState* s, int ma= pping_index) memset(direntry,0,sizeof(direntry_t)); } =20 -/* TODO: if there are more entries, bootsector has to be adjusted! */ -#define ROOT_ENTRIES (0x02 * 0x10 * s->sectors_per_cluster) - if (mapping_index =3D=3D 0 && s->directory.next < ROOT_ENTRIES) { + if (s->fat_type !=3D 32 && + mapping_index =3D=3D 0 && + s->directory.next < s->root_entries) { /* root directory */ int cur =3D s->directory.next; - array_ensure_allocated(&(s->directory), ROOT_ENTRIES - 1); - s->directory.next =3D ROOT_ENTRIES; + array_ensure_allocated(&(s->directory), s->root_entries - 1); + s->directory.next =3D s->root_entries; memset(array_get(&(s->directory), cur), 0, - (ROOT_ENTRIES - cur) * sizeof(direntry_t)); + (s->root_entries - cur) * sizeof(direntry_t)); } =20 /* re-get the mapping, since s->mapping was possibly realloc()ed */ @@ -931,6 +938,8 @@ static int init_directories(BDRVVVFATState* s, /* Now build FAT, and write back information into directory */ init_fat(s); =20 + /* TODO: if there are more entries, bootsector has to be adjusted! *= / + s->root_entries =3D 0x02 * 0x10 * s->sectors_per_cluster; s->cluster_count=3Dsector2cluster(s, s->sector_count); =20 mapping =3D array_get_next(&(s->mapping)); @@ -999,7 +1008,6 @@ static int init_directories(BDRVVVFATState* s, } =20 mapping =3D array_get(&(s->mapping), 0); - s->sectors_of_root_directory =3D mapping->end * s->sectors_per_clust= er; s->last_cluster_of_root_directory =3D mapping->end; =20 /* the FAT signature */ @@ -1018,7 +1026,7 @@ static int init_directories(BDRVVVFATState* s, bootsector->sectors_per_cluster=3Ds->sectors_per_cluster; bootsector->reserved_sectors=3Dcpu_to_le16(1); bootsector->number_of_fats=3D0x2; /* number of FATs */ - bootsector->root_entries=3Dcpu_to_le16(s->sectors_of_root_directory*= 0x10); + bootsector->root_entries =3D cpu_to_le16(s->root_entries); bootsector->total_sectors16=3Ds->sector_count>0xffff?0:cpu_to_le16(s= ->sector_count); /* media descriptor: hard disk=3D0xf8, floppy=3D0xf0 */ bootsector->media_type =3D (s->offset_to_bootsector > 0 ? 0xf8 : 0xf= 0); --=20 1.8.3.1