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In 'perf report', entering a recursive function from inside of itself
(either directly of indirectly through some other function) results in
calling symbol__annotate2 multiple() times, and freeing the whole
disassembly when exiting from the innermost instance.
The first issue causes the function's disassembly to be duplicated, and
the latter a heap use-after-free (and crash) when trying to access the
disassembly again.
I reproduced the bug on perf 5.11.22 (Ubuntu 20.04.3 LTS) and 5.16.rc8
with the following testcase (compile with gcc recursive.c -o recursive).
To reproduce:
- perf record ./recursive
- perf report
- enter fibonacci and annotate it
- move the cursor on one of the "callq fibonacci" instructions and press enter
- at this point there will be two copies of the function in the disassembly
- go back by pressing q, and perf will crash
#include <stdio.h>
int fibonacci(int n)
{
if(n <= 2) return 1;
return fibonacci(n-1) + fibonacci(n-2);
}
int main()
{
printf("%d\n", fibonacci(40));
}
This patch addresses the issue by annotating a function and freeing the
associated memory on exit only if no annotation is already present, so
that a recursive function is only annotated on entry.
Signed-off-by: Dario Petrillo <dario.pk1@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@kernel.org
Link: http://lore.kernel.org/lkml/20220109234441.325106-1-dario.pk1@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.