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| author | Stefan Ott <stefan@ott.net> | 2020-04-04 01:34:33 +0200 |
|---|---|---|
| committer | Solomon Peachy <pizza@shaftnet.org> | 2020-04-07 00:20:13 +0200 |
| commit | 63bf8e4acdbcbfc03e5023291c9ee137f858969f (patch) | |
| tree | 87d67861b88fd6594b06bafac904ed1201c710fe | |
| parent | 180cef835bf40d0081895773aaa637ac926bb0ac (diff) | |
| download | rockbox-63bf8e4acdbcbfc03e5023291c9ee137f858969f.tar.gz rockbox-63bf8e4acdbcbfc03e5023291c9ee137f858969f.zip | |
Consider sector size when checking cluster size
On file systems with 2048 bytes per cluster, the bpb_secperclus value
gets multiplied by 4 when the meta data is loaded. This patch changes
the sanity check to consider (and reverse) that multiplication before
checking the cluster size.
Signed-off-by: Stefan Ott <stefan@ott.net>
| -rw-r--r-- | firmware/drivers/fat.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/firmware/drivers/fat.c b/firmware/drivers/fat.c index fed3baffd4..b14e461a65 100644 --- a/firmware/drivers/fat.c +++ b/firmware/drivers/fat.c @@ -391,7 +391,12 @@ static int bpb_is_sane(struct bpb *fat_bpb) return -1; } - if (fat_bpb->bpb_secperclus * fat_bpb->bpb_bytspersec > 128*1024ul) + /* The fat_bpb struct does not hold the raw value of bpb_bytspersec, the + * value is multiplied in cases where bpb_bytspersec != SECTOR_SIZE. We need + * to undo that multiplication before we do the sanity check. */ + unsigned long secmult = fat_bpb->bpb_bytspersec / SECTOR_SIZE; + + if (fat_bpb->bpb_secperclus * fat_bpb->bpb_bytspersec / secmult > 128*1024ul) { DEBUGF("%s() - Error: cluster size is larger than 128K " "(%lu * %lu = %lu)\n", __func__, |