linux-kernel - [PATCH 1/2] mm: vmalloc: Actually use the in-place vrealloc region

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Message-Id: <20250515214217.619685-1-kees@kernel.org>
Date: Thu, 15 May 2025 14:42:15 -0700
From: Kees Cook <kees@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kees Cook <kees@...nel.org>,
	Shung-Hsi Yu <shung-hsi.yu@...e.com>,
	Eduard Zingerman <eddyz87@...il.com>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Uladzislau Rezki <urezki@...il.com>,
	linux-mm@...ck.org,
	Erhard Furtner <erhard_f@...lbox.org>,
	Danilo Krummrich <dakr@...nel.org>,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH 1/2] mm: vmalloc: Actually use the in-place vrealloc region

The refactoring to not build a new vmalloc region only actually worked
when shrinking. Actually return the resized area when it grows. Ugh.

Reported-by: Shung-Hsi Yu <shung-hsi.yu@...e.com>
Closes: https://lore.kernel.org/all/20250515-bpf-verifier-slowdown-vwo2meju4cgp2su5ckj@6gi6ssxbnfqg
Tested-by: Eduard Zingerman <eddyz87@...il.com>
Tested-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Fixes: a0309faf1cb0 ("mm: vmalloc: support more granular vrealloc() sizing")
Signed-off-by: Kees Cook <kees@...nel.org>
---
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Uladzislau Rezki <urezki@...il.com>
Cc: <linux-mm@...ck.org>
---
 mm/vmalloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2d7511654831..74bd00fd734d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4111,6 +4111,7 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
 		if (want_init_on_alloc(flags))
 			memset((void *)p + old_size, 0, size - old_size);
 		vm->requested_size = size;
+		return (void *)p;
 	}
 
 	/* TODO: Grow the vm_area, i.e. allocate and map additional pages. */
-- 
2.34.1