Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 23/57] tools/lib/lockdep: Reduce MAX_LOCK_DEPTH to avoid overflowing lock_chain/: Depth | Date | Wed, 19 Jul 2017 13:12:29 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Ben Hutchings <ben@decadent.org.uk>
commit 98dcea0cfd04e083ac74137ceb9a632604740e2d upstream.
liblockdep has been broken since commit 75dd602a5198 ("lockdep: Fix lock_chain::base size"), as that adds a check that MAX_LOCK_DEPTH is within the range of lock_chain::depth and in liblockdep it is much too large.
That should have resulted in a compiler error, but didn't because:
- the check uses ARRAY_SIZE(), which isn't yet defined in liblockdep so is assumed to be an (undeclared) function - putting a function call inside a BUILD_BUG_ON() expression quietly turns it into some nonsense involving a variable-length array
It did produce a compiler warning, but I didn't notice because liblockdep already produces too many warnings if -Wall is enabled (which I'll fix shortly).
Even before that commit, which reduced lock_chain::depth from 8 bits to 6, MAX_LOCK_DEPTH was too large.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: a.p.zijlstra@chello.nl Link: http://lkml.kernel.org/r/20170525130005.5947-3-alexander.levin@verizon.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- tools/lib/lockdep/uinclude/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/tools/lib/lockdep/uinclude/linux/lockdep.h +++ b/tools/lib/lockdep/uinclude/linux/lockdep.h @@ -8,7 +8,7 @@ #include <linux/utsname.h> #include <linux/compiler.h> -#define MAX_LOCK_DEPTH 2000UL +#define MAX_LOCK_DEPTH 255UL #define asmlinkage #define __visible
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