Hi,
Static analysis has found a couple of issues as follows:
commit 551f205aff9198e17add1264dd781771d1a2bd9d
Author: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Date: Thu Oct 4 07:43:18 2018 +1000
mm: brk: downgrade mmap_sem to read when shrinking
Static analysis with CoverityScan has detected an issue in mm/mmap.c,
function do_brk_flags():
retval = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
if (retval < 0) {
mm->brk = origbrk;
goto out;
} else if (retval == 1)
downgraded = true;
retval is unsigned long, so the retval < 0 check is always false, which
looks bogus to me.
Also same kind of issue with:
commit e66477708ec2a764d3add92ca59134e3812da0bb
Author: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Date: Thu Oct 4 07:43:18 2018 +1000
mm: mremap: downgrade mmap_sem to read when shrinking
ret = __do_munmap(mm, addr+new_len, old_len - new_len,
&uf_unmap, true);
if (ret < 0 && old_len != new_len)
goto out;
/* Returning 1 indicates mmap_sem is downgraded to read. */
else if (ret == 1)
downgraded = true;
again, ret is unsigned long, so the comparison with ret < 0 is always false.
Detected by CoverityScan, CID#1473794, CID#1473791 "Unsigned compared
against 0".
Colin
