linux-kernel - [PATCH v2] ipc/sem: do not sleep with a spin lock held

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Message-Id: <20211223025623.556044-1-chi.minghao@zte.com.cn>
Date:   Thu, 23 Dec 2021 02:56:23 +0000
From:   cgel.zte@...il.com
To:     manfred@...orfullife.com
Cc:     stable@...r.kernel.org, akpm@...ux-foundation.org, arnd@...db.de,
        cgel.zte@...il.com, chi.minghao@....com.cn, dbueso@...e.de,
        linux-kernel@...r.kernel.org, rdunlap@...radead.org,
        shakeelb@...gle.com, unixbhaskar@...il.com, vvs@...tuozzo.com,
        zealci@....com.cn
Subject: [PATCH v2] ipc/sem: do not sleep with a spin lock held

From: Minghao Chi <chi.minghao@....com.cn>

We can't call kvfree() with a spin lock held, so defer it.
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo
allocation")

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Minghao Chi <chi.minghao@....com.cn>
---
changelog since v2:
+ Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo
+ allocation")
 ipc/sem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 6693daf4fe11..0dbdb98fdf2d 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct
ipc_namespace *ns, int semid)
 	 */
 	un = lookup_undo(ulp, semid);
 	if (un) {
+		spin_unlock(&ulp->lock);
 		kvfree(new);
 		goto success;
 	}
@@ -1976,9 +1977,8 @@ static struct sem_undo *find_alloc_undo(struct
ipc_namespace *ns, int semid)
 	ipc_assert_locked_object(&sma->sem_perm);
 	list_add(&new->list_id, &sma->list_id);
 	un = new;
-
-success:
 	spin_unlock(&ulp->lock);
+success:
 	sem_unlock(sma, -1);
 out:
 	return un;
-- 
2.25.1