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bc187ea6c3
Target core code assumes that target_splice_sess_cmd_list() has set sess_tearing_down and moved the list of pending commands to sess_wait_list, no more commands will be added to the session; if any are added, nothing keeps the se_session from being freed while the command is still in flight, which e.g. leads to use-after-free of se_cmd->se_sess in target_release_cmd_kref(). To enforce this invariant, put a check of sess_tearing_down inside of sess_cmd_lock in target_get_sess_cmd(); any checks before this are racy and can lead to the use-after-free described above. For example, the qla_target check in qlt_do_work() checks sess_tearing_down from work thread context but then drops all locks before calling target_submit_cmd() (as it must, since that is a sleeping function). However, since no locks are held, anything can happen with respect to the session it has looked up -- although it does correctly get sess_kref within its lock, so the memory won't be freed while target_submit_cmd() is actually running, nothing stops eg an ACL from being dropped and calling ->shutdown_session() (which calls into target_splice_sess_cmd_list()) before we get to target_get_sess_cmd(). Once this happens, the se_session memory can be freed as soon as target_submit_cmd() returns and qlt_do_work() drops its reference, even though we've just added a command to sess_cmd_list. To prevent this use-after-free, check sess_tearing_down inside of sess_cmd_lock right before target_get_sess_cmd() adds a command to sess_cmd_list; this is synchronized with target_splice_sess_cmd_list() so that every command is either waited for or not added to the queue. (nab: Keep target_submit_cmd() returning void for now..) Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> |
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| .. | ||
| iscsi | ||
| loopback | ||
| sbp | ||
| tcm_fc | ||
| Kconfig | ||
| Makefile | ||
| target_core_alua.c | ||
| target_core_alua.h | ||
| target_core_configfs.c | ||
| target_core_device.c | ||
| target_core_fabric_configfs.c | ||
| target_core_fabric_lib.c | ||
| target_core_file.c | ||
| target_core_file.h | ||
| target_core_hba.c | ||
| target_core_iblock.c | ||
| target_core_iblock.h | ||
| target_core_internal.h | ||
| target_core_pr.c | ||
| target_core_pr.h | ||
| target_core_pscsi.c | ||
| target_core_pscsi.h | ||
| target_core_rd.c | ||
| target_core_rd.h | ||
| target_core_sbc.c | ||
| target_core_spc.c | ||
| target_core_stat.c | ||
| target_core_tmr.c | ||
| target_core_tpg.c | ||
| target_core_transport.c | ||
| target_core_ua.c | ||
| target_core_ua.h | ||