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authorJack Steiner <steiner@sgi.com>2009-06-17 16:28:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:04:04 -0700
commit1926ee85a903d189c5702eed6531be321e33eb47 (patch)
tree1ae951591d3be09b86479800e2a4f03f119f4d78 /drivers/misc
parentb1b19fcfa417cf62447413d6e8b9b6598adf00b9 (diff)
gru: fix potential use-after-free when purging GRU tlbs
Fix potential SGI GRU bug that could cause a use-after-free. If one thread in a task is flushing the GRU and another thread destroys the GRU context, there is the potential to access a table after it has been freed. Copy the gms pointer to a local variable before unlocking the gts table. Note that no refcnt is needed for the gms - the reference is held indirectly by the task's mm_struct. Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/sgi-gru/grufault.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index 1ad360cd318..679e0177828 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -702,6 +702,7 @@ int gru_user_flush_tlb(unsigned long arg)
{
struct gru_thread_state *gts;
struct gru_flush_tlb_req req;
+ struct gru_mm_struct *gms;
STAT(user_flush_tlb);
if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
@@ -714,8 +715,9 @@ int gru_user_flush_tlb(unsigned long arg)
if (!gts)
return -EINVAL;
- gru_flush_tlb_range(gts->ts_gms, req.vaddr, req.len);
+ gms = gts->ts_gms;
gru_unlock_gts(gts);
+ gru_flush_tlb_range(gms, req.vaddr, req.len);
return 0;
}