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tracing: Fix an unallocated memory access in function_graph 

With CONFIG_DEBUG_PAGEALLOC, I observed an unallocated memory access in
function_graph trace. It appears we find a small size entry in ring buffer,
but we access it as a big size entry. The access overflows the page size
and touches an unallocated page.

Cc: <stable@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
LKML-Reference: <1280217994.32400.76.camel@sli10-desk.sh.intel.com>
[ Added a comment to explain the problem - SDR ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Shaohua Li 2010-07-27 16:06:34 +08:00 committed by Steven Rostedt
parent 8a4fd31e0e
commit 575570f027
1 changed files with 9 additions and 1 deletions
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10
kernel/trace/trace_functions_graph.c
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@ -507,7 +507,15 @@ get_return_for_leaf(struct trace_iterator *iter,
* if the output fails.
*/
data->ent = *curr;
data->ret = *next;
/*
* If the next event is not a return type, then
* we only care about what type it is. Otherwise we can
* safely copy the entire event.
*/
if (next->ent.type == TRACE_GRAPH_RET)
data->ret = *next;
else
data->ret.ent.type = next->ent.type;
}
}