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Import commit from NetBSD with checkin message:

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Avoid Undefined Behavior in ffs_clusteracct()

    Change the type of 'bit' variable from int to unsigned int and use unsigned
    values consistently.

    sys/ufs/ffs/ffs_subr.c:336:10, shift exponent -1 is negative

    Detected with Kernel Undefined Behavior Sanitizer.

    Reported by <Harry Pantazis>

Submitted by: Pedro Giffuni
This commit is contained in:
mckusick 2018-07-07 19:11:43 +00:00
parent fee608954f
commit 658dc4c073
1 changed files with 5 additions and 4 deletions
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9
sys/ufs/ffs/ffs_subr.c
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@ -473,7 +473,8 @@ ffs_clusteracct(struct fs *fs, struct cg *cgp, ufs1_daddr_t blkno, int cnt)
int32_t *sump;
int32_t *lp;
u_char *freemapp, *mapp;
int i, start, end, forw, back, map, bit;
int i, start, end, forw, back, map;
u_int bit;
if (fs->fs_contigsumsize <= 0)
return;
@ -495,7 +496,7 @@ ffs_clusteracct(struct fs *fs, struct cg *cgp, ufs1_daddr_t blkno, int cnt)
end = cgp->cg_nclusterblks;
mapp = &freemapp[start / NBBY];
map = *mapp++;
bit = 1 << (start % NBBY);
bit = 1U << (start % NBBY);
for (i = start; i < end; i++) {
if ((map & bit) == 0)
break;
@ -516,7 +517,7 @@ ffs_clusteracct(struct fs *fs, struct cg *cgp, ufs1_daddr_t blkno, int cnt)
end = -1;
mapp = &freemapp[start / NBBY];
map = *mapp--;
bit = 1 << (start % NBBY);
bit = 1U << (start % NBBY);
for (i = start; i > end; i--) {
if ((map & bit) == 0)
break;
@ -524,7 +525,7 @@ ffs_clusteracct(struct fs *fs, struct cg *cgp, ufs1_daddr_t blkno, int cnt)
bit >>= 1;
} else {
map = *mapp--;
bit = 1 << (NBBY - 1);
bit = 1U << (NBBY - 1);
}
}
back = start - i;