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author | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-11-06 10:37:59 +0300 |
---|---|---|
committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-11-29 06:33:15 +0300 |
commit | 057085e522f8bf94c2e691a5b76880f68060f8ba (patch) | |
tree | d813e53ee7853a19eb2697e71bd2851b8acc5cc6 /drivers/target/target_core_sbc.c | |
parent | ca82c2bded29b38d36140bfa1e76a7bbfcade390 (diff) | |
download | linux-057085e522f8bf94c2e691a5b76880f68060f8ba.tar.xz |
target: Fix race for SCF_COMPARE_AND_WRITE_POST checking
This patch addresses a race + use after free where the first
stage of COMPARE_AND_WRITE in compare_and_write_callback()
is rescheduled after the backend sends the secondary WRITE,
resulting in second stage compare_and_write_post() callback
completing in target_complete_ok_work() before the first
can return.
Because current code depends on checking se_cmd->se_cmd_flags
after return from se_cmd->transport_complete_callback(),
this results in first stage having SCF_COMPARE_AND_WRITE_POST
set, which incorrectly falls through into second stage CAW
processing code, eventually triggering a NULL pointer
dereference due to use after free.
To address this bug, pass in a new *post_ret parameter into
se_cmd->transport_complete_callback(), and depend upon this
value instead of ->se_cmd_flags to determine when to return
or fall through into ->queue_status() code for CAW.
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/target_core_sbc.c')
-rw-r--r-- | drivers/target/target_core_sbc.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 0b4b2a67d9f9..ae24d0fdcd76 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -371,7 +371,8 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o return 0; } -static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success) +static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success, + int *post_ret) { unsigned char *buf, *addr; struct scatterlist *sg; @@ -437,7 +438,8 @@ sbc_execute_rw(struct se_cmd *cmd) cmd->data_direction); } -static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) +static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, + int *post_ret) { struct se_device *dev = cmd->se_dev; @@ -447,8 +449,10 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) * sent to the backend driver. */ spin_lock_irq(&cmd->t_state_lock); - if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) + if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) { cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; + *post_ret = 1; + } spin_unlock_irq(&cmd->t_state_lock); /* @@ -460,7 +464,8 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) return TCM_NO_SENSE; } -static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success) +static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success, + int *post_ret) { struct se_device *dev = cmd->se_dev; struct scatterlist *write_sg = NULL, *sg; |