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Commit 94dbf7c0 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
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btrfs: free the allocated memory if btrfs_alloc_page_array() fails



[BUG]
If btrfs_alloc_page_array() fail to allocate all pages but part of the
slots, then the partially allocated pages would be leaked in function
btrfs_submit_compressed_read().

[CAUSE]
As explicitly stated, if btrfs_alloc_page_array() returned -ENOMEM,
caller is responsible to free the partially allocated pages.

For the existing call sites, most of them are fine:

- btrfs_raid_bio::stripe_pages
  Handled by free_raid_bio().

- extent_buffer::pages[]
  Handled btrfs_release_extent_buffer_pages().

- scrub_stripe::pages[]
  Handled by release_scrub_stripe().

But there is one exception in btrfs_submit_compressed_read(), if
btrfs_alloc_page_array() failed, we didn't cleanup the array and freed
the array pointer directly.

Initially there is still the error handling in commit dd137dd1
("btrfs: factor out allocating an array of pages"), but later in commit
544fe4a9 ("btrfs: embed a btrfs_bio into struct compressed_bio"),
the error handling is removed, leading to the possible memory leak.

[FIX]
This patch would add back the error handling first, then to prevent such
situation from happening again, also
Make btrfs_alloc_page_array() to free the allocated pages as a extra
safety net, then we don't need to add the error handling to
btrfs_submit_compressed_read().

Fixes: 544fe4a9 ("btrfs: embed a btrfs_bio into struct compressed_bio")
CC: stable@vger.kernel.org # 6.4+
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 5de0434b
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