From nobody Mon Oct 6 21:00:47 2025 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2274B2F3C1D for ; Wed, 16 Jul 2025 15:25:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752679503; cv=none; b=AXZgw/QBxAM9JY9D24lLU/9fB1vH3GTqF1B5KFuElpeqLHz/EmNZgWlDpafr4oGTPkCvhNP3NHcBUdgDw8DeNmgDj3PVJ2tXDX7Rg3Ua+ykp0a9YYDQaDif3Ef/rT7fDfTV6pmHwilIeg+pw6UOu8b6pyOAKNXHT1UeE3WyFrew= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752679503; c=relaxed/simple; bh=ohTqHGpgfY4UUTSymbW6sLvYas+aSmBkVgsQzVj/EzI=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=hCqi53bqlIJadAwOtB2Y7+Njov7UwO5FMS+fBFOAyWqE+AeRR/8KuTqGQj1lMZUIOalCCH6iFiUgTKUnsI/NnVz44nANbmNhCWaBiMWmlfjvo4pTPGvFWY82cG+pYijNAaYD2fcVeyePVr6YXWd07BiCn4J1FuZ10wln3Ca9SFg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--elver.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=0okP4Ksd; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--elver.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="0okP4Ksd" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-451d30992bcso53510735e9.2 for ; Wed, 16 Jul 2025 08:25:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1752679499; x=1753284299; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=Y020Ei9Bk/dDr2jy5oIxQhB4Mux4H8qkRk2Nk2X5B6Y=; b=0okP4KsdUGJdMFYyp3757/SLW9tmoJF3u4SeogKjlC13Dm0j+IXTdSsHPmzSP4ezRx hjBdkwb7heBkseLwDCZCUHDNNehiR0mRrcJGuGzFWfa1nSXYAp4sMgd6kMXjrSuoAWkh lcXmvQuYC65HD0P/2JeyaJFAEUA+hoWsNO2gRGclJrDnomk6nDhFBsdy/CupAUJaXNUs s8oYP9goIM8MbILYl/IzqIkr6MelPgifG78QIH5aQgfOvl+ysOVJ3MGeFjh1/ruOsShY PT7xhY/LgMg3t09JgHTHJigJGI6jtIyjb8XzQOuJwZ/+4cgmrTvpJFHrZk4wkZ0tOyRi IvoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752679499; x=1753284299; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=Y020Ei9Bk/dDr2jy5oIxQhB4Mux4H8qkRk2Nk2X5B6Y=; b=dZ3bwg++KkNiCZaFYLNjwbiAYUs3TTxNLenHcjUU3g8fyfSOOrCkF8jlikh9w++aL7 lA5UAIpJ2ogVL6MsNIJEadZBvz5E6/Lf5bCbMJJpfB0bvu0m7rgzmSuKnhjmY9GxmV4C y0+Une9YMFabsnQL4wwG4xb3RUKdukhHPQ3+f4+p6PbnHNl/4w96ZXqJ2LPvJnWNB4LJ eM/Nm8kTXFAwVN1HCbtJ9uZkXsJNrHXZByk4bxUDaRXFXBWi9azwIaPF8KBtQnw1oqZW ATuOskja/Dxdg0T3TOgvM9ysgo6Eg2L9wE4DrkIR11xtjD6ST6Kxe0tv8sh5Jblo9R1S 8rSQ== X-Forwarded-Encrypted: i=1; AJvYcCWjVaHV7kBFFK+LCBG1qEUTXdv5Ss8dtFsfhfceD+hThuElf4cekuCHGfyGdeumgNM7+aGsypnuD9INeWM=@vger.kernel.org X-Gm-Message-State: AOJu0Yz+TZOvfM4XySxCfxYNVpdLpuMG7HhxDLdE3/6pF5InG/QuoHNb kLhTRuRjKtBUlinHyFtM5CLDZkfJCeXieSzP+IkwyUIjdEIP8vqBH2ydvKjDD6Bu7obbhNmU7wP jiA== X-Google-Smtp-Source: AGHT+IG+qln5bQT2mE9wIX8K89bRFDCyEmW+N27eenT0Mz+MKpFiGEtyXe0L5xsEE6EDOAbOFijYhxLGLw== X-Received: from wmbhe13.prod.google.com ([2002:a05:600c:540d:b0:43c:ef7b:ffac]) (user=elver job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:19cb:b0:43c:ee3f:2c3 with SMTP id 5b1f17b1804b1-4562e37a0ecmr26916265e9.7.1752679499601; Wed, 16 Jul 2025 08:24:59 -0700 (PDT) Date: Wed, 16 Jul 2025 17:23:28 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250716152448.3877201-1-elver@google.com> Subject: [PATCH] kasan: use vmalloc_dump_obj() for vmalloc error reports From: Marco Elver To: elver@google.com, Andrew Morton Cc: Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , Andrey Konovalov , Vincenzo Frascino , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Uladzislau Rezki , Sebastian Andrzej Siewior , Yeoreum Yun , Yunseong Kim , stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Since 6ee9b3d84775 ("kasan: remove kasan_find_vm_area() to prevent possible deadlock"), more detailed info about the vmalloc mapping and the origin was dropped due to potential deadlocks. While fixing the deadlock is necessary, that patch was too quick in killing an otherwise useful feature, and did no due-diligence in understanding if an alternative option is available. Restore printing more helpful vmalloc allocation info in KASAN reports with the help of vmalloc_dump_obj(). Example report: | BUG: KASAN: vmalloc-out-of-bounds in vmalloc_oob+0x4c9/0x610 | Read of size 1 at addr ffffc900002fd7f3 by task kunit_try_catch/493 | | CPU: [...] | Call Trace: | | dump_stack_lvl+0xa8/0xf0 | print_report+0x17e/0x810 | kasan_report+0x155/0x190 | vmalloc_oob+0x4c9/0x610 | [...] | | The buggy address belongs to a 1-page vmalloc region starting at 0xffffc9= 00002fd000 allocated at vmalloc_oob+0x36/0x610 | The buggy address belongs to the physical page: | page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1263= 64 | flags: 0x200000000000000(node=3D0|zone=3D2) | raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000 | raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 | page dumped because: kasan: bad access detected | | [..] Fixes: 6ee9b3d84775 ("kasan: remove kasan_find_vm_area() to prevent possibl= e deadlock") Suggested-by: Uladzislau Rezki Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Sebastian Andrzej Siewior Cc: Yeoreum Yun Cc: Yunseong Kim Cc: Signed-off-by: Marco Elver Acked-by: Andrey Ryabinin Acked-by: Uladzislau Rezki (Sony) --- mm/kasan/report.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/kasan/report.c b/mm/kasan/report.c index b0877035491f..62c01b4527eb 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -399,7 +399,9 @@ static void print_address_description(void *addr, u8 ta= g, } =20 if (is_vmalloc_addr(addr)) { - pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n", a= ddr); + pr_err("The buggy address belongs to a"); + if (!vmalloc_dump_obj(addr)) + pr_cont(" vmalloc virtual mapping\n"); page =3D vmalloc_to_page(addr); } =20 --=20 2.50.0.727.gbf7dc18ff4-goog