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misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and gru_handle_user_call_os

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In some bad situation, the gts may be freed gru_check_chiplet_assignment.
The call chain can be gru_unload_context->gru_free_gru_context->gts_drop
and kfree finally. However, the caller didn't know if the gts is freed
or not and use it afterwards. This will trigger a Use after Free bug.

Fix it by introducing a return value to see if it's in error path or not.
Free the gts in caller if gru_check_chiplet_assignment check failed.

Fixes: 55484c45db ("gru: allow users to specify gru chiplet 2")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Link: https://lore.kernel.org/r/20221110035033.19498-1-zyytlz.wz@163.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zheng Wang 2022-11-10 11:50:33 +08:00 committed by Greg Kroah-Hartman
parent fd2c930cf6
commit 643a16a0eb
3 changed files with 30 additions and 7 deletions
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13
drivers/misc/sgi-gru/grufault.c
View File

@ -648,6 +648,7 @@ int gru_handle_user_call_os(unsigned long cb)
if ((cb & (GRU_HANDLE_STRIDE - 1)) || ucbnum >= GRU_NUM_CB)
return -EINVAL;
again:
gts = gru_find_lock_gts(cb);
if (!gts)
return -EINVAL;
@ -656,7 +657,11 @@ int gru_handle_user_call_os(unsigned long cb)
if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE)
goto exit;
gru_check_context_placement(gts);
if (gru_check_context_placement(gts)) {
gru_unlock_gts(gts);
gru_unload_context(gts, 1);
goto again;
}
/*
* CCH may contain stale data if ts_force_cch_reload is set.
@ -874,7 +879,11 @@ int gru_set_context_option(unsigned long arg)
} else {
gts->ts_user_blade_id = req.val1;
gts->ts_user_chiplet_id = req.val0;
gru_check_context_placement(gts);
if (gru_check_context_placement(gts)) {
gru_unlock_gts(gts);
gru_unload_context(gts, 1);
return ret;
}
}
break;
case sco_gseg_owner:

22
drivers/misc/sgi-gru/grumain.c
View File

@ -716,9 +716,10 @@ static int gru_check_chiplet_assignment(struct gru_state *gru,
* chiplet. Misassignment can occur if the process migrates to a different
* blade or if the user changes the selected blade/chiplet.
*/
void gru_check_context_placement(struct gru_thread_state *gts)
int gru_check_context_placement(struct gru_thread_state *gts)
{
struct gru_state *gru;
int ret = 0;
/*
* If the current task is the context owner, verify that the
@ -726,15 +727,23 @@ void gru_check_context_placement(struct gru_thread_state *gts)
* references. Pthread apps use non-owner references to the CBRs.
*/
gru = gts->ts_gru;
/*
* If gru or gts->ts_tgid_owner isn't initialized properly, return
* success to indicate that the caller does not need to unload the
* gru context.The caller is responsible for their inspection and
* reinitialization if needed.
*/
if (!gru || gts->ts_tgid_owner != current->tgid)
return;
return ret;
if (!gru_check_chiplet_assignment(gru, gts)) {
STAT(check_context_unload);
gru_unload_context(gts, 1);
ret = -EINVAL;
} else if (gru_retarget_intr(gts)) {
STAT(check_context_retarget_intr);
}
return ret;
}
@ -934,7 +943,12 @@ again:
mutex_lock(&gts->ts_ctxlock);
preempt_disable();
gru_check_context_placement(gts);
if (gru_check_context_placement(gts)) {
preempt_enable();
mutex_unlock(&gts->ts_ctxlock);
gru_unload_context(gts, 1);
return VM_FAULT_NOPAGE;
}
if (!gts->ts_gru) {
STAT(load_user_context);

2
drivers/misc/sgi-gru/grutables.h
View File

@ -632,7 +632,7 @@ extern int gru_user_flush_tlb(unsigned long arg);
extern int gru_user_unload_context(unsigned long arg);
extern int gru_get_exception_detail(unsigned long arg);
extern int gru_set_context_option(unsigned long address);
extern void gru_check_context_placement(struct gru_thread_state *gts);
extern int gru_check_context_placement(struct gru_thread_state *gts);
extern int gru_cpu_fault_map_id(void);
extern struct vm_area_struct *gru_find_vma(unsigned long vaddr);
extern void gru_flush_all_tlb(struct gru_state *gru);