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btrfs: check folio mapping after unlock in put_file_data()

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commit 0fba7be1ca6df2881e68386e5575fe096f33c4ca upstream.

When we call btrfs_read_folio() we get an unlocked folio, so it is possible
for a different thread to concurrently modify folio->mapping. We must
check that this hasn't happened once we do have the lock.

CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Boris Burkov
2024-12-13 12:33:22 -08:00
committed by Greg Kroah-Hartman
parent c3a403d8ce
commit dd8bbfe723
1 changed files with 6 additions and 0 deletions
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fs/btrfs/send.c
+6
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@@ -5291,6 +5291,7 @@ static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
unsigned cur_len = min_t(unsigned, len,
PAGE_SIZE - pg_offset);
again:
folio = filemap_lock_folio(mapping, index);
if (IS_ERR(folio)) {
page_cache_sync_readahead(mapping,
@@ -5323,6 +5324,11 @@ static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
ret = -EIO;
break;
}
if (folio->mapping != mapping) {
folio_unlock(folio);
folio_put(folio);
goto again;
}
}
memcpy_from_folio(sctx->send_buf + sctx->send_size, folio,