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smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=oWwJSQpn; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=9Tx/kwrv; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="oWwJSQpn"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="9Tx/kwrv" Date: Mon, 24 Feb 2025 19:44:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1740426287; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MkCaQhgnBjzfMYc4PqAZZY6fDGmDOTFNpKwKCoDSqwY=; b=oWwJSQpniA8qYGApEdIe/93Zb3+xPinzC/sEZq4ZSjOy3iY4hB+geyG3jKyjV0JF8dnNaO ypyMhd91fcgwUEvpNnVMCyhL0zMtzEcCIfeoJhuLXqaKuLiHZetjUtbbqA5D23anzv3+IS opbP2YRay16A6uYKm2W4zjEoASUyWHLSpwy6hlLi7US4ZYPBLj6N3DPojuBy+AdnRGbxZ/ bNd2T88ex8uQAYHOpBmDseecNQD0s4Yvi2bS+/PecbDjXVpVG4exiGDbttQtxb7IaTPBTw zjtbKraeAXWKI0zOYXywnbe9V4JIPlSnqzh5QkjGpRmXAh6Tq/+PIxaDoj5/pQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1740426287; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MkCaQhgnBjzfMYc4PqAZZY6fDGmDOTFNpKwKCoDSqwY=; b=9Tx/kwrvivc9r5QdgnQz5RBXZmyBUHOa/QLLOif6TenZGPR+KxBGDZmEGzjiKCpeZnszlB DdBADsTcik2drQDQ== From: "tip-bot2 for Tong Tiangen" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] uprobes: Reject the shared zeropage in uprobe_write_opcode() Cc: Tong Tiangen , Ingo Molnar , David Hildenbrand , Oleg Nesterov , Peter Zijlstra , Masami Hiramatsu , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250224031149.1598949-1-tongtiangen@huawei.com> References: <20250224031149.1598949-1-tongtiangen@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174042628408.10177.12444069940449647418.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the perf/urgent branch of tip: Commit-ID: bddf10d26e6e5114e7415a0e442ec6f51a559468 Gitweb: https://git.kernel.org/tip/bddf10d26e6e5114e7415a0e442ec6f51= a559468 Author: Tong Tiangen AuthorDate: Mon, 24 Feb 2025 11:11:49 +08:00 Committer: Ingo Molnar CommitterDate: Mon, 24 Feb 2025 20:37:45 +01:00 uprobes: Reject the shared zeropage in uprobe_write_opcode() We triggered the following crash in syzkaller tests: BUG: Bad page state in process syz.7.38 pfn:1eff3 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3 flags: 0x3fffff00004004(referenced|reserved|node=3D0|zone=3D1|lastcpupid= =3D0x1fffff) raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000 raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubunt= u1.1 04/01/2014 Call Trace: dump_stack_lvl+0x32/0x50 bad_page+0x69/0xf0 free_unref_page_prepare+0x401/0x500 free_unref_page+0x6d/0x1b0 uprobe_write_opcode+0x460/0x8e0 install_breakpoint.part.0+0x51/0x80 register_for_each_vma+0x1d9/0x2b0 __uprobe_register+0x245/0x300 bpf_uprobe_multi_link_attach+0x29b/0x4f0 link_create+0x1e2/0x280 __sys_bpf+0x75f/0xac0 __x64_sys_bpf+0x1a/0x30 do_syscall_64+0x56/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1 The following syzkaller test case can be used to reproduce: r2 =3D creat(&(0x7f0000000000)=3D'./file0\x00', 0x8) write$nbd(r2, &(0x7f0000000580)=3DANY=3D[], 0x10) r4 =3D openat(0xffffffffffffff9c, &(0x7f0000000040)=3D'./file0\x00', 0x42= , 0x0) mmap$IORING_OFF_SQ_RING(&(0x7f0000ffd000/0x3000)=3Dnil, 0x3000, 0x0, 0x12= , r4, 0x0) r5 =3D userfaultfd(0x80801) ioctl$UFFDIO_API(r5, 0xc018aa3f, &(0x7f0000000040)=3D{0xaa, 0x20}) r6 =3D userfaultfd(0x80801) ioctl$UFFDIO_API(r6, 0xc018aa3f, &(0x7f0000000140)) ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, &(0x7f0000000100)=3D{{&(0x7f0000ffc= 000/0x4000)=3Dnil, 0x4000}, 0x2}) ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, &(0x7f0000000000)=3D{{&(0x7f0000ffd= 000/0x1000)=3Dnil, 0x1000}}) r7 =3D bpf$PROG_LOAD(0x5, &(0x7f0000000140)=3D{0x2, 0x3, &(0x7f0000000200= )=3DANY=3D[@ANYBLOB=3D"1800000000120000000000000000000095"], &(0x7f00000000= 00)=3D'GPL\x00', 0x7, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @fallback=3D0x30, 0x= ffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x= 10, 0x0, @void, @value}, 0x94) bpf$BPF_LINK_CREATE_XDP(0x1c, &(0x7f0000000040)=3D{r7, 0x0, 0x30, 0x1e, @= val=3D@uprobe_multi=3D{&(0x7f0000000080)=3D'./file0\x00', &(0x7f0000000100)= =3D[0x2], 0x0, 0x0, 0x1}}, 0x40) The cause is that zero pfn is set to the PTE without increasing the RSS count in mfill_atomic_pte_zeropage() and the refcount of zero folio does not increase accordingly. Then, the operation on the same pfn is performed in uprobe_write_opcode()->__replace_page() to unconditional decrease the RSS count and old_folio's refcount. Therefore, two bugs are introduced: 1. The RSS count is incorrect, when process exit, the check_mm() report error "Bad rss-count". 2. The reserved folio (zero folio) is freed when folio->refcount is zero, then free_pages_prepare->free_page_is_bad() report error "Bad page state". There is more, the following warning could also theoretically be triggered: __replace_page() -> ... -> folio_remove_rmap_pte() -> VM_WARN_ON_FOLIO(is_zero_folio(folio), folio) Considering that uprobe hit on the zero folio is a very rare case, just reject zero old folio immediately after get_user_page_vma_remote(). [ mingo: Cleaned up the changelog ] Fixes: 7396fa818d62 ("uprobes/core: Make background page replacement logic = account for rss_stat counters") Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remo= ve uprobes breakpoints") Signed-off-by: Tong Tiangen Signed-off-by: Ingo Molnar Reviewed-by: David Hildenbrand Reviewed-by: Oleg Nesterov Cc: Peter Zijlstra Cc: Masami Hiramatsu Link: https://lore.kernel.org/r/20250224031149.1598949-1-tongtiangen@huawei= .com --- kernel/events/uprobes.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index bf2a87a..af53fbd 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -495,6 +495,11 @@ retry: if (ret <=3D 0) goto put_old; =20 + if (is_zero_page(old_page)) { + ret =3D -EINVAL; + goto put_old; + } + if (WARN(!is_register && PageCompound(old_page), "uprobe unregister should never work on compound page\n")) { ret =3D -EINVAL;