Hello,

On Wed, 02 May 2012 19:17:41 -0700 Aaron Williams Aaron.Williams@cavium.com wrote:

This patch fixes several issues where sector offsets can overflow due to being limited to 16-bits. There are many cases which can cause an overflow, including large FAT32 partitions and partitions that start at a sufficiently large offset on the storage device.

For large FAT32 partitions only changing of fatlength, rootdir_sect and data_begin is needed to avoid overflows. Changing of fat_sect shouldn't be needed.

What do you mean exactly by "partitions starting at a sufficiently large offset on the storage device"? How do you create such partition? I've tested with a 210 GB FAT32 partition as the fourth primary partition on a 2 TB disk. This partition is the last partition on the disk, so its offset is sufficiently large. For this test only fatlength, rootdir_sect and data_begin was changed to __u32 and int and I do not see issues when listing or loading the files from this partition.

Numerous issues were observed and fixed when a 64GB FAT32 filesystem was accessed due to truncation.

Signed-off-by: Aaron Williams aaron.williams@caviumnetworks.com

include/fat.h | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/fat.h b/include/fat.h index 4c92442..7215628 100644 --- a/include/fat.h +++ b/include/fat.h @@ -178,12 +178,12 @@ typedef struct dir_slot { typedef struct { __u8 *fatbuf; /* Current FAT buffer */ int fatsize; /* Size of FAT in bits */

•   __u16   fatlength;      /* Length of FAT in sectors */
  

•   __u16   fat_sect;       /* Starting sector of the FAT */
  

•   __u16   rootdir_sect;   /* Start sector of root directory */
  

•   __u16   sect_size;      /* Size of sectors in bytes */
  

•   __u32   fat_sect;       /* Starting sector of the FAT */
  

•   __u32   rootdir_sect;   /* Start sector of root directory */
  

•   __u32   fatlength;      /* Length of FAT in sectors */
    __u16   clust_size;     /* Size of clusters in sectors */
  

•   short   data_begin;     /* The sector of the first cluster, can be negative */
  

•   __u16   sect_size;      /* Size of sectors in bytes */
  

•   int     data_begin;     /* The sector of the first cluster, can be negative */
    int     fatbufnum;      /* Used by get_fatent, init to -1 */
  

} fsdata;

The patch is probably corrupted by your mailer, it doesn't apply.

Thanks, Anatolij

From: Aaron Williams aaron.williams@caviumnetworks.com

This patch fixes several issues where sector offsets can overflow due to being limited to 16-bits. The cases where an overflow can happen when accessing large FAT32 partitions are:

- length of FAT in sectors - start sector of root directory - the sector of the first cluster

These issues were observed when reading files from a 64GB FAT32 filesystem.

Signed-off-by: Aaron Williams aaron.williams@caviumnetworks.com Tested-by: Anatolij Gustschin agust@denx.de Signed-off-by: Anatolij Gustschin agust@denx.de --- include/fat.h | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/fat.h b/include/fat.h index 4c92442..f1b4a0d 100644 --- a/include/fat.h +++ b/include/fat.h @@ -178,12 +178,12 @@ typedef struct dir_slot { typedef struct { __u8 *fatbuf; /* Current FAT buffer */ int fatsize; /* Size of FAT in bits */ - __u16 fatlength; /* Length of FAT in sectors */ + __u32 fatlength; /* Length of FAT in sectors */ __u16 fat_sect; /* Starting sector of the FAT */ - __u16 rootdir_sect; /* Start sector of root directory */ + __u32 rootdir_sect; /* Start sector of root directory */ __u16 sect_size; /* Size of sectors in bytes */ __u16 clust_size; /* Size of clusters in sectors */ - short data_begin; /* The sector of the first cluster, can be negative */ + int data_begin; /* The sector of the first cluster, can be negative */ int fatbufnum; /* Used by get_fatent, init to -1 */ } fsdata;