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fs: check FAT cluster size

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The cluster size specifies how many sectors make up a cluster.  A
cluster size of zero makes no sense, as it would mean that the
cluster is made up of no sectors.  This will later lead into a
division by zero in sect_to_clust(), so better take care of that
early.

The MAX_CLUSTSIZE define can reduced using a define to make some
room in low-memory system.  Unfortunately if the code reads a
filesystem with a bigger cluster size it will overflow the buffer.

Signed-off-by: Patrick Wildt <patrick@blueri.se>
This commit is contained in:
Patrick Wildt 2018-11-26 15:56:57 +01:00 committed by Tom Rini
parent 16462a3572
commit cd80a4fe61
1 changed files with 11 additions and 0 deletions
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11
fs/fat/fat.c
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@ -571,6 +571,17 @@ static int get_fs_info(fsdata *mydata)
mydata->sect_size, cur_part_info.blksz);
return -1;
}
if (mydata->clust_size == 0) {
printf("Error: FAT cluster size not set\n");
return -1;
}
if ((unsigned int)mydata->clust_size * mydata->sect_size >
MAX_CLUSTSIZE) {
printf("Error: FAT cluster size too big (cs=%u, max=%u)\n",
(unsigned int)mydata->clust_size * mydata->sect_size,
MAX_CLUSTSIZE);
return -1;
}
if (mydata->fatsize == 32) {
mydata->data_begin = mydata->rootdir_sect -