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Rafael Aquini
0a1805b580
JIRA: https://redhat.atlassian.net/browse/RHEL-145694 CVE: CVE-2025-39941 commit ce4be9e4307c5a60701ff6e0cafa74caffdc54ce Author: Sergey Senozhatsky <senozhatsky@chromium.org> Date: Tue Sep 9 13:48:35 2025 +0900 zram: fix slot write race condition Parallel concurrent writes to the same zram index result in leaked zsmalloc handles. Schematically we can have something like this: CPU0 CPU1 zram_slot_lock() zs_free(handle) zram_slot_lock() zram_slot_lock() zs_free(handle) zram_slot_lock() compress compress handle = zs_malloc() handle = zs_malloc() zram_slot_lock zram_set_handle(handle) zram_slot_lock zram_slot_lock zram_set_handle(handle) zram_slot_lock Either CPU0 or CPU1 zsmalloc handle will leak because zs_free() is done too early. In fact, we need to reset zram entry right before we set its new handle, all under the same slot lock scope. Link: https://lkml.kernel.org/r/20250909045150.635345-1-senozhatsky@chromium.org Fixes: 71268035f5d7 ("zram: free slot memory early during write") Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reported-by: Changhui Zhong <czhong@redhat.com> Closes: https://lore.kernel.org/all/CAGVVp+UtpGoW5WEdEU7uVTtsSCjPN=ksN6EcvyypAtFDOUf30A@mail.gmail.com/ Tested-by: Changhui Zhong <czhong@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rafael Aquini <raquini@redhat.com>