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btrfs: exit after state split error at btrfs_convert_extent_bit()

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If split_state() returned an error we call extent_io_tree_panic() which
will trigger a BUG() call. However if CONFIG_BUG is disabled, which is an
uncommon and exotic scenario, then we fallthrough and hit a use after free
when calling set_state_bits() since the extent state record which the
local variable 'prealloc' points to was freed by split_state().

So jump to the label 'out' after calling extent_io_tree_panic() and set
the 'prealloc' pointer to NULL since split_state() has already freed it
when it hit an error.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana
2025-04-10 17:01:59 +01:00
committed by David Sterba
parent 5f9c554a6c
commit 2a72dd9996
1 changed files with 4 additions and 1 deletions
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5
fs/btrfs/extent-io-tree.c
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@@ -1460,8 +1460,11 @@ int btrfs_convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
}
ret = split_state(tree, state, prealloc, end + 1);
if (ret)
if (ret) {
extent_io_tree_panic(tree, state, "split", ret);
prealloc = NULL;
goto out;
}
set_state_bits(tree, prealloc, bits, NULL);
cache_state(prealloc, cached_state);