diff options
| author | Stefan Brüns <stefan.bruens@rwth-aachen.de> | 2016-12-17 00:27:50 +0100 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2016-12-27 11:24:13 -0500 |
| commit | 6c1a808052ba6a875df7aa450b6df4b199f3a281 (patch) | |
| tree | 92e632f3ade5970513c8e6058f3946196a19d98b | |
| parent | c99d1b3ccf8d6fda809bb391da9cde86157cc4c9 (diff) | |
fs/fat: Avoid corruption of sectors following the FAT
The FAT is read/flushed in segments of 6 (FATBUFBLOCKS) disk sectors. The
last segment may be less than 6 sectors, cap the length.
Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
| -rw-r--r-- | fs/fat/fat.c | 1 | ||||
| -rw-r--r-- | fs/fat/fat_write.c | 22 |
2 files changed, 13 insertions, 10 deletions
diff --git a/fs/fat/fat.c b/fs/fat/fat.c index df9f2b5656..6319581406 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -202,6 +202,7 @@ static __u32 get_fatent(fsdata *mydata, __u32 entry) __u32 fatlength = mydata->fatlength; __u32 startblock = bufnum * FATBUFBLOCKS; + /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */ if (startblock + getsize > fatlength) getsize = fatlength - startblock; diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index aab0b0e71d..4605020854 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -117,10 +117,11 @@ static int flush_dirty_fat_buffer(fsdata *mydata) if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1)) return 0; - startblock += mydata->fat_sect; + /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */ + if (startblock + getsize > fatlength) + getsize = fatlength - startblock; - if (getsize > fatlength) - getsize = fatlength; + startblock += mydata->fat_sect; /* Write FAT buf */ if (disk_write(startblock, getsize, bufptr) < 0) { @@ -187,8 +188,9 @@ static __u32 get_fatent_value(fsdata *mydata, __u32 entry) __u32 fatlength = mydata->fatlength; __u32 startblock = bufnum * FATBUFBLOCKS; - if (getsize > fatlength) - getsize = fatlength; + /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */ + if (startblock + getsize > fatlength) + getsize = fatlength - startblock; startblock += mydata->fat_sect; /* Offset from start of disk */ @@ -499,15 +501,15 @@ static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value) __u32 fatlength = mydata->fatlength; __u32 startblock = bufnum * FATBUFBLOCKS; - fatlength *= mydata->sect_size; - startblock += mydata->fat_sect; - - if (getsize > fatlength) - getsize = fatlength; + /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */ + if (startblock + getsize > fatlength) + getsize = fatlength - startblock; if (flush_dirty_fat_buffer(mydata) < 0) return -1; + startblock += mydata->fat_sect; + if (disk_read(startblock, getsize, bufptr) < 0) { debug("Error reading FAT blocks\n"); return -1; |