linux-kernel - [PATCH 2/5] kmsan: fix usage of kmsan_enter_runtime() in kmsan_vmap_pages_range

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Message-ID: <20250507160012.3311104-2-glider@google.com>
Date: Wed,  7 May 2025 18:00:09 +0200
From: Alexander Potapenko <glider@...gle.com>
To: glider@...gle.com
Cc: elver@...gle.com, dvyukov@...gle.com, bvanassche@....org, 
	kent.overstreet@...ux.dev, iii@...ux.ibm.com, akpm@...ux-foundation.org, 
	linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com
Subject: [PATCH 2/5] kmsan: fix usage of kmsan_enter_runtime() in kmsan_vmap_pages_range_noflush()

Only enter the runtime to call __vmap_pages_range_noflush(), so that error
handling does not skip kmsan_leave_runtime().

This bug was spotted by CONFIG_WARN_CAPABILITY_ANALYSIS=y

Cc: Marco Elver <elver@...gle.com>
Cc: Bart Van Assche <bvanassche@....org>
Cc: Kent Overstreet <kent.overstreet@...ux.dev>
Signed-off-by: Alexander Potapenko <glider@...gle.com>
---
 mm/kmsan/shadow.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/kmsan/shadow.c b/mm/kmsan/shadow.c
index 6d32bfc18d6a2..54f3c3c962f07 100644
--- a/mm/kmsan/shadow.c
+++ b/mm/kmsan/shadow.c
@@ -247,17 +247,19 @@ int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
 	kmsan_enter_runtime();
 	mapped = __vmap_pages_range_noflush(shadow_start, shadow_end, prot,
 					    s_pages, page_shift);
+	kmsan_leave_runtime();
 	if (mapped) {
 		err = mapped;
 		goto ret;
 	}
+	kmsan_enter_runtime();
 	mapped = __vmap_pages_range_noflush(origin_start, origin_end, prot,
 					    o_pages, page_shift);
+	kmsan_leave_runtime();
 	if (mapped) {
 		err = mapped;
 		goto ret;
 	}
-	kmsan_leave_runtime();
 	flush_tlb_kernel_range(shadow_start, shadow_end);
 	flush_tlb_kernel_range(origin_start, origin_end);
 	flush_cache_vmap(shadow_start, shadow_end);
-- 
2.49.0.967.g6a0df3ecc3-goog