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b1fb2c52b2
Currently if some one try to advance bvec beyond it's size we simply
dump WARN_ONCE and continue to iterate beyond bvec array boundaries.
This simply means that we endup dereferencing/corrupting random memory
region.
Sane reaction would be to propagate error back to calling context
But bvec_iter_advance's calling context is not always good for error
handling. For safity reason let truncate iterator size to zero which
will break external iteration loop which prevent us from unpredictable
memory range corruption. And even it caller ignores an error, it will
corrupt it's own bvecs, not others.
This patch does:
- Return error back to caller with hope that it will react on this
- Truncate iterator size
Code was added long time ago here 4550dd6c, luckily no one hit it
in real life :)
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
[hch: switch to true/false returns instead of errno values]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
101 lines
2.8 KiB
C
101 lines
2.8 KiB
C
/*
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* bvec iterator
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*
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* Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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*
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public Licens
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
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*/
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#ifndef __LINUX_BVEC_ITER_H
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#define __LINUX_BVEC_ITER_H
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#include <linux/kernel.h>
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#include <linux/bug.h>
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#include <linux/errno.h>
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/*
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* was unsigned short, but we might as well be ready for > 64kB I/O pages
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*/
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struct bio_vec {
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struct page *bv_page;
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unsigned int bv_len;
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unsigned int bv_offset;
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};
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struct bvec_iter {
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sector_t bi_sector; /* device address in 512 byte
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sectors */
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unsigned int bi_size; /* residual I/O count */
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unsigned int bi_idx; /* current index into bvl_vec */
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unsigned int bi_bvec_done; /* number of bytes completed in
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current bvec */
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};
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/*
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* various member access, note that bio_data should of course not be used
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* on highmem page vectors
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*/
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#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
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#define bvec_iter_page(bvec, iter) \
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(__bvec_iter_bvec((bvec), (iter))->bv_page)
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#define bvec_iter_len(bvec, iter) \
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min((iter).bi_size, \
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__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
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#define bvec_iter_offset(bvec, iter) \
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(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
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#define bvec_iter_bvec(bvec, iter) \
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((struct bio_vec) { \
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.bv_page = bvec_iter_page((bvec), (iter)), \
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.bv_len = bvec_iter_len((bvec), (iter)), \
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.bv_offset = bvec_iter_offset((bvec), (iter)), \
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})
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static inline bool bvec_iter_advance(const struct bio_vec *bv,
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struct bvec_iter *iter, unsigned bytes)
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{
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if (WARN_ONCE(bytes > iter->bi_size,
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"Attempted to advance past end of bvec iter\n")) {
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iter->bi_size = 0;
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return false;
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}
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while (bytes) {
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unsigned iter_len = bvec_iter_len(bv, *iter);
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unsigned len = min(bytes, iter_len);
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bytes -= len;
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iter->bi_size -= len;
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iter->bi_bvec_done += len;
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if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
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iter->bi_bvec_done = 0;
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iter->bi_idx++;
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}
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}
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return true;
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}
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#define for_each_bvec(bvl, bio_vec, iter, start) \
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for (iter = (start); \
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(iter).bi_size && \
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((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
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bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
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#endif /* __LINUX_BVEC_ITER_H */
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