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Correct a regression in the previous change, r322459. Specifically, the

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removal of the "blk" parameter from blst_meta_alloc() had the unintended
effect of generating an out-of-range allocation when the cursor reaches
the end of the tree if the number of managed blocks in the tree equals
the so-called "radix" (which in the blist code is not the standard notion
of what a radix is but rather the maximum number of leaves in a tree of
the current height.)  In other words, only certain swap configurations
were affected, which is why earlier testing did not reveal the problem.

Submitted by:	Doug Moore <dougm@rice.edu>
Reported by:	pho, kib
Tested by:	pho
X-MFC with:	r322459
Differential Revision:	https://reviews.freebsd.org/D12106
This commit is contained in:
Alan Cox 2017-08-25 18:47:23 +00:00
parent c7e10205ae
commit a0ae476b7e
1 changed files with 2 additions and 0 deletions
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2
sys/kern/subr_blist.c
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@ -251,6 +251,8 @@ blist_alloc(blist_t bl, daddr_t count)
bl->bl_radix);
if (blk != SWAPBLK_NONE) {
bl->bl_cursor = blk + count;
if (bl->bl_cursor == bl->bl_blocks)
bl->bl_cursor = 0;
return (blk);
} else if (bl->bl_cursor != 0)
bl->bl_cursor = 0;