ide-io: set REQ_FAILED when drive is dead
Currently it's possible to ide-cd to set an incorrect blocksize by reading garbage if the drive is dead: ide_cd_probe() -> cdrom_read_toc() -> cdrom_read_capacity() -> cdrom_queue_packet_command() -> ide_do_drive_cmd() -> ide_do_request() -> start_request() on start_request(): /* bail early if we've exceeded max_failures */ if (drive->max_failures && (drive->failures > drive->max_failures)) { goto kill_rq; } (...) kill_rq: ide_kill_rq(drive, rq); return ide_stopped; ide_kill_rq() and the next calls won't set REQ_FAILED on rq->cmd_flags and thus cdrom_queue_packet_command() won't return an error. then: stat = cdrom_queue_packet_command(drive, &req); if (stat == 0) { *capacity = 1 + be32_to_cpu(capbuf.lba); *sectors_per_frame = be32_to_cpu(capbuf.blocklen) >> SECTOR_BITS; } cdrom_read_capacity() ends believing capbuf is valid but in fact it's just uninitialized data. back to cdrom_read_toc(): /* Try to get the total cdrom capacity and sector size. */ stat = cdrom_read_capacity(drive, &toc->capacity, §ors_per_frame, sense); if (stat) toc->capacity = 0x1fffff; set_capacity(info->disk, toc->capacity * sectors_per_frame); /* Save a private copy of te TOC capacity for error handling */ drive->probed_capacity = toc->capacity * sectors_per_frame; blk_queue_hardsect_size(drive->queue, sectors_per_frame << SECTOR_BITS); that will set drive->queue->hardsect_size to be the random value. hardsect_size is used to calculate inode->i_blkbits. later on, on a read path: void create_empty_buffers(struct page *page, unsigned long blocksize, unsigned long b_state) { struct buffer_head *bh, *head, *tail; head = alloc_page_buffers(page, blocksize, 1); bh = head; do { bh->b_state |= b_state; tail = bh; bh = bh->b_this_page; } while (bh); tail->b_this_page = head; alloc_page_buffers() will return NULL if blocksize > 4096. blocksize is calculed based on inode->i_blkbits. that will trigger a null dereference on create_empty_buffers(). Signed-off-by: Aristeu Rozanski <arozansk@redhat.com> Cc: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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@ -1003,6 +1003,7 @@ static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
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/* bail early if we've exceeded max_failures */
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/* bail early if we've exceeded max_failures */
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if (drive->max_failures && (drive->failures > drive->max_failures)) {
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if (drive->max_failures && (drive->failures > drive->max_failures)) {
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rq->cmd_flags |= REQ_FAILED;
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goto kill_rq;
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goto kill_rq;
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}
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}
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