s390/mm: Fix memory leak in add_marker() when kvrealloc() fails

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commit 07ad45e06b upstream.

The function has a memory leak when kvrealloc() fails.
The function directly assigns NULL to the markers pointer, losing the
reference to the previously allocated memory. This causes kvfree() in
pt_dump_init() to free NULL instead of the leaked memory.

Fix by:
1. Using kvrealloc() uniformly for all allocations
2. Using a temporary variable to preserve the original pointer until
   allocation succeeds
3. Removing the error path that sets markers_cnt=0 to keep
   consistency between markers and markers_cnt

Found via static analysis and this is similar to commit 42378a9ca5
("bpf, verifier: Fix memory leak in array reallocation for stack state")

Fixes: d0e7915d2a ("s390/mm/ptdump: Generate address marker array dynamically")
Cc: stable@vger.kernel.org
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Miaoqian Lin 2025-10-27 23:08:38 +08:00 • committed by Greg Kroah-Hartman

parent a16e92f8d7

commit 7eb7ee2bbd

1 changed files with 7 additions and 12 deletions

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arch/s390/mm/dump_pagetables.c

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