From nobody Sun Dec 14 19:16:01 2025 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 53B297CF16 for ; Thu, 12 Dec 2024 01:38:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733967502; cv=none; b=rwSOWYUuPnSkjRAIkUhcmmHA7SyP5rWD/5IBtbxwFudp7QJypZO1Z7aCGVxkBkBqONVMMPIb+DH2S/CDlx48oa3N2CtCTzYt7RPCfaG/CktlU+eIMFr3si9319bKViJLzhVKxMYypR09SfGQQnSmd76MKHhTIWW1WXURCOe/Ztk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733967502; c=relaxed/simple; bh=Xx2WlBa15PynuyV1qtYoACDIplVhi1qnUeEYPrRsX10=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=W07FFy4E2z5sPoneOd+6gW42qm1ofo55gD0YbbufTA3JwsaH46RdDqnPnPdIlRR6Q8bx/qyqoeiBrRzMOvbJZKiHG3aS+YTDUr8x2xKo9F6I+0nmaGAONHrvdy2F2TEctLc4afOKFAkIbAdhRnA/t/L4hrl3+Pdz28bD2PIeM2w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=VCFRbxkM; arc=none smtp.client-ip=91.218.175.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="VCFRbxkM" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1733967495; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eFSCeKh2XG4V4HSsQcvawPOsbfqsyYaaE6SNHpbCJWw=; b=VCFRbxkMxMnqGeN6WIi6CWEH8GGv7QFnflIuyzUiMEb7nq03ypAekfZaBBzWUPgPvoq8zi EDjJrReKx+/kBH0rFA6Dg+FrHekKKnKGURsKHIAitqu2X+qhkYrCDhzr0v+L1QsCCh2Rck iAzU0N0Rz0C2Ag4Rq4+bkfNlPQyrNMk= From: Hao Ge To: surenb@google.com, kent.overstreet@linux.dev, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, hao.ge@linux.dev, Hao Ge , Ben Greear Subject: [PATCH v4] mm/alloc_tag: Fix panic when CONFIG_KASAN enabled and CONFIG_KASAN_VMALLOC not enabled Date: Thu, 12 Dec 2024 09:37:23 +0800 Message-Id: <20241212013723.113408-1-hao.ge@linux.dev> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Hao Ge When CONFIG_KASAN is enabled but CONFIG_KASAN_VMALLOC is not enabled, we may encounter a panic during system boot. Because we haven't allocated pages and created mappings for the shadow memory corresponding to module_tags region, similar to how it is done for execmem_vmalloc. The difference is that our module_tags are allocated on demand, so similarly,we also need to allocate shadow memory regions on demand. However, we still need to adhere to the MODULE_ALIGN principle. Here is the log for panic: [ 18.349421] BUG: unable to handle page fault for address: fffffbfff80920= 00 [ 18.350016] #PF: supervisor read access in kernel mode [ 18.350459] #PF: error_code(0x0000) - not-present page [ 18.350904] PGD 20fe52067 P4D 219dc8067 PUD 219dc4067 PMD 102495067 PTE 0 [ 18.351484] Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 18.351961] CPU: 5 UID: 0 PID: 1 Comm: systemd Not tainted 6.13.0-rc1+ #3 [ 18.352533] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS = rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 18.353494] RIP: 0010:kasan_check_range+0xba/0x1b0 [ 18.353931] Code: 8d 5a 07 4c 0f 49 da 49 c1 fb 03 45 85 db 0f 84 dd 00 = 00 00 45 89 db 4a 8d 14 d8 eb 0d 48 83 c0 08 48 39 c2 0f 84 c1 00 00 00 <48= > 83 38 00 74 ed 48 8d 50 08 eb 0d 48 83 c0 01 48 39 d0 0f 84 90 [ 18.355484] RSP: 0018:ff11000101877958 EFLAGS: 00010206 [ 18.355937] RAX: fffffbfff8092000 RBX: fffffbfff809201e RCX: ffffffff82a= 7ceac [ 18.356542] RDX: fffffbfff8092018 RSI: 00000000000000f0 RDI: ffffffffc04= 90000 [ 18.357153] RBP: fffffbfff8092000 R08: 0000000000000001 R09: fffffbfff80= 9201d [ 18.357756] R10: ffffffffc04900ef R11: 0000000000000003 R12: ffffffffc04= 90000 [ 18.358365] R13: ff11000101877b48 R14: ffffffffc0490000 R15: 00000000000= 0002c [ 18.358968] FS: 00007f9bd13c5940(0000) GS:ff110001eb480000(0000) knlGS:= 0000000000000000 [ 18.359648] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 18.360178] CR2: fffffbfff8092000 CR3: 0000000109214004 CR4: 00000000007= 71ef0 [ 18.360790] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000000= 00000 [ 18.361404] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 00000000000= 00400 [ 18.362020] PKRU: 55555554 [ 18.362261] Call Trace: [ 18.362481] [ 18.362671] ? __die+0x23/0x70 [ 18.362964] ? page_fault_oops+0xc2/0x160 [ 18.363318] ? exc_page_fault+0xad/0xc0 [ 18.363680] ? asm_exc_page_fault+0x26/0x30 [ 18.364056] ? move_module+0x3cc/0x8a0 [ 18.364398] ? kasan_check_range+0xba/0x1b0 [ 18.364755] __asan_memcpy+0x3c/0x60 [ 18.365074] move_module+0x3cc/0x8a0 [ 18.365386] layout_and_allocate.constprop.0+0x3d5/0x720 [ 18.365841] ? early_mod_check+0x3dc/0x510 [ 18.366195] load_module+0x72/0x1850 [ 18.366509] ? __pfx_kernel_read_file+0x10/0x10 [ 18.366918] ? vm_mmap_pgoff+0x21c/0x2d0 [ 18.367262] init_module_from_file+0xd1/0x130 [ 18.367638] ? __pfx_init_module_from_file+0x10/0x10 [ 18.368073] ? __pfx__raw_spin_lock+0x10/0x10 [ 18.368456] ? __pfx_cred_has_capability.isra.0+0x10/0x10 [ 18.368938] idempotent_init_module+0x22c/0x790 [ 18.369332] ? simple_getattr+0x6f/0x120 [ 18.369676] ? __pfx_idempotent_init_module+0x10/0x10 [ 18.370110] ? fdget+0x58/0x3a0 [ 18.370393] ? security_capable+0x64/0xf0 [ 18.370745] __x64_sys_finit_module+0xc2/0x140 [ 18.371136] do_syscall_64+0x7d/0x160 [ 18.371459] ? fdget_pos+0x1c8/0x4c0 [ 18.371784] ? ksys_read+0xfd/0x1d0 [ 18.372106] ? syscall_exit_to_user_mode+0x10/0x1f0 [ 18.372525] ? do_syscall_64+0x89/0x160 [ 18.372860] ? do_syscall_64+0x89/0x160 [ 18.373194] ? do_syscall_64+0x89/0x160 [ 18.373527] ? syscall_exit_to_user_mode+0x10/0x1f0 [ 18.373952] ? do_syscall_64+0x89/0x160 [ 18.374283] ? syscall_exit_to_user_mode+0x10/0x1f0 [ 18.374701] ? do_syscall_64+0x89/0x160 [ 18.375037] ? do_user_addr_fault+0x4a8/0xa40 [ 18.375416] ? clear_bhb_loop+0x25/0x80 [ 18.375748] ? clear_bhb_loop+0x25/0x80 [ 18.376119] ? clear_bhb_loop+0x25/0x80 [ 18.376450] entry_SYSCALL_64_after_hwframe+0x76/0x7e Fixes: 233e89322cbe ("alloc_tag: fix module allocation tags populated area = calculation") Reported-by: Ben Greear Closes: https://lore.kernel.org/all/1ba0cc57-e2ed-caa2-1241-aa5615bee01f@ca= ndelatech.com/ Suggested-by: Suren Baghdasaryan Signed-off-by: Hao Ge --- v4: Based on Suren's suggestion for modification (to make the code simpler), modify the code. Update the comments in the code due to the modifications made to the co= de. Add Suggested-by: Suren Baghdasaryan v3: Adjusting the title because the previous one was a bit unclear. Suren has pointed out that our condition for determining whether to allocate shadow memory is unreasonable.We have adjusted our method to use every 8 pages as an index (idx), and we will make decisions based on this idx when determining whether to allocate shadow memory. v2: Add comments to facilitate understanding of the code. Add align nr << PAGE_SHIFT to MODULE_ALIGN,even though kasan_alloc_modu= le_shadow already handles this internally,but to make the code more readable and = user-friendly commit 233e89322cbe ("alloc_tag: fix module allocation tags populated area calculation") is currently in the mm-hotfixes-unstable branch, so this patch is developed based on the mm-hotfixes-unstable branch. --- lib/alloc_tag.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index f942408b53ef..c5bdfa297a35 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -407,6 +407,8 @@ static int vm_module_tags_populate(void) =20 if (phys_end < new_end) { struct page **next_page =3D vm_module_tags->pages + vm_module_tags->nr_p= ages; + unsigned long old_shadow_end =3D ALIGN(phys_end, MODULE_ALIGN); + unsigned long new_shadow_end =3D ALIGN(new_end, MODULE_ALIGN); unsigned long more_pages; unsigned long nr; =20 @@ -421,7 +423,19 @@ static int vm_module_tags_populate(void) __free_page(next_page[i]); return -ENOMEM; } + vm_module_tags->nr_pages +=3D nr; + + /* + * Kasan allocates 1 byte of shadow for every 8 bytes of data. + * When kasan_alloc_module_shadow allocates shadow memory, + * its unit of allocation is a page. + * Therefore, here we need to align to MODULE_ALIGN. + */ + if (old_shadow_end < new_shadow_end) + kasan_alloc_module_shadow((void *)old_shadow_end, + new_shadow_end - old_shadow_end, + GFP_KERNEL); } =20 /* --=20 2.25.1