linux-kernel - [PATCH] PM: hibernate: Fix crash when freeing invalid crypto compressor

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Message-ID: <20251224182055.124020-1-mrout@redhat.com>
Date: Wed, 24 Dec 2025 23:50:54 +0530
From: Malaya Kumar Rout <mrout@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: mrout@...hat.com,
	malayarout91@...il.com,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Pavel Machek <pavel@...nel.org>,
	linux-pm@...r.kernel.org
Subject: [PATCH] PM: hibernate: Fix crash when freeing invalid crypto compressor

When crypto_alloc_acomp() fails, it returns an ERR_PTR value, not NULL.
The cleanup code in save_compressed_image() and load_compressed_image()
unconditionally calls crypto_free_acomp() without checking for ERR_PTR,
which causes crypto_acomp_tfm() to dereference an invalid pointer and
crash the kernel.

This can be triggered when the compression algorithm is unavailable
(e.g., CONFIG_CRYPTO_LZO not enabled).

Fix by adding IS_ERR_OR_NULL() checks before calling crypto_free_acomp()
and acomp_request_free(), similar to the existing kthread_stop() check.

Signed-off-by: Malaya Kumar Rout <mrout@...hat.com>
---
 kernel/power/swap.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 33a186373bef..8ee2fa995580 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -902,8 +902,10 @@ static int save_compressed_image(struct swap_map_handle *handle,
 		for (thr = 0; thr < nr_threads; thr++) {
 			if (data[thr].thr)
 				kthread_stop(data[thr].thr);
-			acomp_request_free(data[thr].cr);
-			crypto_free_acomp(data[thr].cc);
+			if (data[thr].cr)
+				acomp_request_free(data[thr].cr);
+			if (!IS_ERR_OR_NULL(data[thr].cc))
+				crypto_free_acomp(data[thr].cc);
 		}
 		vfree(data);
 	}
@@ -1499,8 +1501,10 @@ static int load_compressed_image(struct swap_map_handle *handle,
 		for (thr = 0; thr < nr_threads; thr++) {
 			if (data[thr].thr)
 				kthread_stop(data[thr].thr);
-			acomp_request_free(data[thr].cr);
-			crypto_free_acomp(data[thr].cc);
+			if (data[thr].cr)
+				acomp_request_free(data[thr].cr);
+			if (!IS_ERR_OR_NULL(data[thr].cc))
+				crypto_free_acomp(data[thr].cc);
 		}
 		vfree(data);
 	}
-- 
2.51.0