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libext2fs: fix binary search for the icount and badblocks stores 

Remove the interpolation because there is a bug in icount which can
cause a core dump if calculated range gets turned into a NaN and then
do an out-of-bounds array access.  We could fix this with some more
tests, but the complexity is such that nuking all of the interpolation
code will be faster than fixing the interpolation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
bitmap-optimize
Theodore Ts'o 2011-08-31 14:27:21 -04:00
parent 9b3018a82e
commit a4aff9ca5b
2 changed files with 2 additions and 26 deletions
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2
lib/ext2fs/badblocks.c
View File

@ -177,7 +177,7 @@ int ext2fs_u32_list_find(ext2_u32_list bb, __u32 blk)
return high;
while (low < high) {
mid = (low+high)/2;
mid = ((unsigned)low + (unsigned)high)/2;
if (mid == low || mid == high)
break;
if (blk == bb->list[mid])

26
lib/ext2fs/icount.c
View File

@ -363,31 +363,7 @@ static struct ext2_icount_el *get_icount_el(ext2_icount_t icount,
low = 0;
high = (int) icount->count-1;
while (low <= high) {
#if 0
mid = (low+high)/2;
#else
if (low == high)
mid = low;
else {
/* Interpolate for efficiency */
lowval = icount->list[low].ino;
highval = icount->list[high].ino;
if (ino < lowval)
range = 0;
else if (ino > highval)
range = 1;
else {
range = ((float) (ino - lowval)) /
(highval - lowval);
if (range > 0.9)
range = 0.9;
if (range < 0.1)
range = 0.1;
}
mid = low + ((int) (range * (high-low)));
}
#endif
mid = ((unsigned)low + (unsigned)high) >> 1;
if (ino == icount->list[mid].ino) {
icount->cursor = mid+1;
return &icount->list[mid];