This is a note to let you know that I've just added the patch titled misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and gru_handle_user_call_os to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: misc-sgi-gru-fix-use-after-free-error-in-gru_set_con.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 14df393305c7086e7a156b3dfb1bc980ac45a860 Author: Zheng Wang <zyytlz.wz@xxxxxxx> Date: Thu Nov 10 11:50:33 2022 +0800 misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and gru_handle_user_call_os [ Upstream commit 643a16a0eb1d6ac23744bb6e90a00fc21148a9dc ] 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: 55484c45dbec ("gru: allow users to specify gru chiplet 2") Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx> Acked-by: Dimitri Sivanich <sivanich@xxxxxxx> Link: https://lore.kernel.org/r/20221110035033.19498-1-zyytlz.wz@xxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index d7ef61e602ed..b836936e9747 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -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: diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c index 9afda47efbf2..3a16eb8e03f7 100644 --- a/drivers/misc/sgi-gru/grumain.c +++ b/drivers/misc/sgi-gru/grumain.c @@ -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 @@ vm_fault_t gru_fault(struct vm_fault *vmf) mutex_lock(>s->ts_ctxlock); preempt_disable(); - gru_check_context_placement(gts); + if (gru_check_context_placement(gts)) { + preempt_enable(); + mutex_unlock(>s->ts_ctxlock); + gru_unload_context(gts, 1); + return VM_FAULT_NOPAGE; + } if (!gts->ts_gru) { STAT(load_user_context); diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h index e4c067c61251..5c9783150cdf 100644 --- a/drivers/misc/sgi-gru/grutables.h +++ b/drivers/misc/sgi-gru/grutables.h @@ -638,7 +638,7 @@ 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);