diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-11-21 12:41:26 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-11-24 11:04:54 +0100 |
| commit | bca4104b00fec60be330cd32818dd5c70db3d469 (patch) | |
| tree | f9e831af7baf488267fbfe0bcac55dab0a0ad0d7 /kernel/locking | |
| parent | 98b1cc82c4affc16f5598d4fa14b1858671b2263 (diff) | |
lockdep: Fix block chain corruption
Kent reported an occasional KASAN splat in lockdep. Mark then noted:
> I suspect the dodgy access is to chain_block_buckets[-1], which hits the last 4
> bytes of the redzone and gets (incorrectly/misleadingly) attributed to
> nr_large_chain_blocks.
That would mean @size == 0, at which point size_to_bucket() returns -1
and the above happens.
alloc_chain_hlocks() has 'size - req', for the first with the
precondition 'size >= rq', which allows the 0.
This code is trying to split a block, del_chain_block() takes what we
need, and add_chain_block() puts back the remainder, except in the
above case the remainder is 0 sized and things go sideways.
Fixes: 810507fe6fd5 ("locking/lockdep: Reuse freed chain_hlocks entries")
Reported-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lkml.kernel.org/r/20231121114126.GH8262@noisy.programming.kicks-ass.net
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/lockdep.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index e85b5ad3e206..151bd3de5936 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3497,7 +3497,8 @@ static int alloc_chain_hlocks(int req) size = chain_block_size(curr); if (likely(size >= req)) { del_chain_block(0, size, chain_block_next(curr)); - add_chain_block(curr + req, size - req); + if (size > req) + add_chain_block(curr + req, size - req); return curr; } } |