Re: [PATCH v2] s390/mm: Fix memory leak in add_marker() when kvrealloc fails

[Heiko Carstens]

On Mon, Oct 27, 2025 at 11:08:38PM +0800, Miaoqian Lin wrote:
> 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 42378a9ca553
> ("bpf, verifier: Fix memory leak in array reallocation for stack state")
> 
> Fixes: d0e7915d2ad3 ("s390/mm/ptdump: Generate address marker array dynamically")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Miaoqian Lin <linmq006@xxxxxxxxx>
> ---
> changes in v2:
> - update the fixing logic to prevent memory leak in v1
> v1 link: https://lore.kernel.org/all/20251026091351.36275-1-linmq006@xxxxxxxxx/
> ---
>  arch/s390/mm/dump_pagetables.c | 22 +++++++++-------------
>  1 file changed, 9 insertions(+), 13 deletions(-)

Applied, thanks!