From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) (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 C55BF20E31C for ; Sat, 19 Oct 2024 00:47:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729298837; cv=none; b=frvpqgG2n/HntyGUiBUX2Vo5+BT8b4/gPwMyHtxWePqXT5WwIG8YQgG32nLjGlg9JZTuZU6pniW7UOVYjXyyFJzYCT/UlC85kEvzJiy/8yiyetuh/VxeY8GfFdu7Wx6Iughhw1MYwsb5xFS+RRHjEuN73peok4W3R6PKL73XeX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729298837; c=relaxed/simple; bh=MWkc4kgSdYY1yY5/8fZILHwaGX69K2uYbgzuUy1Xg2g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=W6l3z8VXjmYy+loB89NgJeu7xrdyu2Jg0VqXAxKYpBltKSWr+9qK6vNiJF9IJVYKXKwZPIQpKC4AwmQw6uSBr5vlJKIv5QNtTwHT6Vlgaw7i5MQWEzywwNyHbo8/qOPbXLmzRMv7ujMx8/xncM6D3hy1LxqwCIMRnNPzjPayPuQ= 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=UQbF/m9a; arc=none smtp.client-ip=95.215.58.183 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="UQbF/m9a" Message-ID: <2f771446-be6a-3b7c-4595-be8c8188145a@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1729298832; h=from:from: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=/EFA0Vboc98xveNpC5j8v99xfq8WC2DXWWIW59XaPa8=; b=UQbF/m9aBp2wwPK2nX/EDFTe0ZDcXloTBaw30su5QZcHQwyAnoMq7OrCQzigKT9wJthTcL mD66NBPZMcZ8DYC8PssNN+hyZioYpiiZ5j8gJKFaoaolZAObalt3GcdEgnkzpBRetRTq93 WLrTRmnYHeuNl3q3ZfMgd7gwULexKS0= Date: Sat, 19 Oct 2024 08:46:43 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2] mm/codetag: move ref and tag null pointer check to alloc_tag_add To: Suren Baghdasaryan Cc: kent.overstreet@linux.dev, akpm@linux-foundation.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Ge References: <20241018152925.138341-1-hao.ge@linux.dev> <20241018162559.143548-1-hao.ge@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Hao Ge In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Hi Suren On 10/19/24 01:30, Suren Baghdasaryan wrote: > On Fri, Oct 18, 2024 at 9:26 AM Hao Ge wrote: >> From: Hao Ge >> >> When we compile and load lib/slub_kunit.c,it will cause a panic. >> >> The root cause is that __kmalloc_cache_noprof was directly called >> instead of kmem_cache_alloc,which resulted in no alloc_tag being >> allocated.This caused current->alloc_tag to be null,leading to a >> null pointer dereference in alloc_tag_ref_set. >> >> Despite the fact that my colleague Pei Xiao will later fix the code >> in slub_kunit.c,we still need to move the null pointer check for ref >> and tag to alloc_tag_add here. >> It is sufficient for us to issue a warning to the user; >> It should not lead to a panic. >> >> Here is the log for the panic: >> >> [ 74.779373][ T2158] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020 >> [ 74.780130][ T2158] Mem abort info: >> [ 74.780406][ T2158] ESR = 0x0000000096000004 >> [ 74.780756][ T2158] EC = 0x25: DABT (current EL), IL = 32 bits >> [ 74.781225][ T2158] SET = 0, FnV = 0 >> [ 74.781529][ T2158] EA = 0, S1PTW = 0 >> [ 74.781836][ T2158] FSC = 0x04: level 0 translation fault >> [ 74.782288][ T2158] Data abort info: >> [ 74.782577][ T2158] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 >> [ 74.783068][ T2158] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >> [ 74.783533][ T2158] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >> [ 74.784010][ T2158] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000105f34000 >> [ 74.784586][ T2158] [0000000000000020] pgd=0000000000000000, p4d=0000000000000000 >> [ 74.785293][ T2158] Internal error: Oops: 0000000096000004 [#1] SMP >> [ 74.785805][ T2158] Modules linked in: slub_kunit kunit ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_mangle 4 >> [ 74.790661][ T2158] CPU: 0 UID: 0 PID: 2158 Comm: kunit_try_catch Kdump: loaded Tainted: G W N 6.12.0-rc3+ #2 >> [ 74.791535][ T2158] Tainted: [W]=WARN, [N]=TEST >> [ 74.791889][ T2158] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 >> [ 74.792479][ T2158] pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> [ 74.793101][ T2158] pc : alloc_tagging_slab_alloc_hook+0x120/0x270 >> [ 74.793607][ T2158] lr : alloc_tagging_slab_alloc_hook+0x120/0x270 >> [ 74.794095][ T2158] sp : ffff800084d33cd0 >> [ 74.794418][ T2158] x29: ffff800084d33cd0 x28: 0000000000000000 x27: 0000000000000000 >> [ 74.795095][ T2158] x26: 0000000000000000 x25: 0000000000000012 x24: ffff80007b30e314 >> [ 74.795822][ T2158] x23: ffff000390ff6f10 x22: 0000000000000000 x21: 0000000000000088 >> [ 74.796555][ T2158] x20: ffff000390285840 x19: fffffd7fc3ef7830 x18: ffffffffffffffff >> [ 74.797283][ T2158] x17: ffff8000800e63b4 x16: ffff80007b33afc4 x15: ffff800081654c00 >> [ 74.798011][ T2158] x14: 0000000000000000 x13: 205d383531325420 x12: 5b5d383734363537 >> [ 74.798744][ T2158] x11: ffff800084d337e0 x10: 000000000000005d x9 : 00000000ffffffd0 >> [ 74.799476][ T2158] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008219d188 x6 : c0000000ffff7fff >> [ 74.800206][ T2158] x5 : ffff0003fdbc9208 x4 : ffff800081edd188 x3 : 0000000000000001 >> [ 74.800932][ T2158] x2 : 0beaa6dee1ac5a00 x1 : 0beaa6dee1ac5a00 x0 : ffff80037c2cb000 >> [ 74.801656][ T2158] Call trace: >> [ 74.801954][ T2158] alloc_tagging_slab_alloc_hook+0x120/0x270 >> [ 74.802494][ T2158] __kmalloc_cache_noprof+0x148/0x33c >> [ 74.802976][ T2158] test_kmalloc_redzone_access+0x4c/0x104 [slub_kunit] >> [ 74.803607][ T2158] kunit_try_run_case+0x70/0x17c [kunit] >> [ 74.804124][ T2158] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit] >> [ 74.804768][ T2158] kthread+0x10c/0x118 >> [ 74.805141][ T2158] ret_from_fork+0x10/0x20 >> [ 74.805540][ T2158] Code: b9400a80 11000400 b9000a80 97ffd858 (f94012d3) >> [ 74.806176][ T2158] SMP: stopping secondary CPUs >> [ 74.808130][ T2158] Starting crashdump kernel... >> >> Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") >> Signed-off-by: Hao Ge >> --- >> v2: Modify the errors in the title and commit message. >> Remove the empty lines that were mistakenly added in version v1. >> --- >> include/linux/alloc_tag.h | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h >> index 1f0a9ff23a2c..8603e3a9df10 100644 >> --- a/include/linux/alloc_tag.h >> +++ b/include/linux/alloc_tag.h >> @@ -137,10 +137,6 @@ static inline void alloc_tag_sub_check(union codetag_ref *ref) {} >> /* Caller should verify both ref and tag to be valid */ >> static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag) >> { >> - alloc_tag_add_check(ref, tag); >> - if (!ref || !tag) >> - return; >> - > Unfortunately this change will result in __alloc_tag_ref_set() and > alloc_tag_ref_set() missing the following important check from > alloc_tag_sub_check(): > Maybe I missed something here, I'm a bit confused. Can you give me an example to explain it? Thanks Best regards Hao > WARN_ONCE(ref && ref->ct, > "alloc_tag was not cleared (got tag for %s:%u)\n", > ref->ct->filename, ref->ct->lineno); > > I think the change below would fix this issue without the above > mentioned side-effect: > > -static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct > alloc_tag *tag) > +static inline bool __alloc_tag_ref_set(union codetag_ref *ref, struct > alloc_tag *tag) > { > alloc_tag_add_check(ref, tag); > if (!ref || !tag) > - return; > + return false; > > ref->ct = &tag->ct; > + return true; > } > > -static inline void alloc_tag_ref_set(union codetag_ref *ref, struct > alloc_tag *tag) > +static inline bool alloc_tag_ref_set(union codetag_ref *ref, struct > alloc_tag *tag) > { > - __alloc_tag_ref_set(ref, tag); > + if (unlikely(!__alloc_tag_ref_set(ref, tag))) > + return false; > + > /* > * We need in increment the call counter every time we have a new > * allocation or when we split a large allocation into smaller ones. > * Each new reference for every sub-allocation needs to increment call > * counter because when we free each part the counter will be > decremented. > */ > this_cpu_inc(tag->counters->calls); > + return true; > } > > static inline void alloc_tag_add(union codetag_ref *ref, struct > alloc_tag *tag, size_t bytes) > { > - alloc_tag_ref_set(ref, tag); > - this_cpu_add(tag->counters->bytes, bytes); > + if (likely(alloc_tag_ref_set(ref, tag))) > + this_cpu_add(tag->counters->bytes, bytes); > } > > Could you please confirm this fix? > Thanks, > Suren. > >> ref->ct = &tag->ct; >> } >> >> @@ -158,6 +154,10 @@ static inline void alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *t >> >> static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag, size_t bytes) >> { >> + alloc_tag_add_check(ref, tag); >> + if (!ref || !tag) >> + return; >> + >> alloc_tag_ref_set(ref, tag); >> this_cpu_add(tag->counters->bytes, bytes); >> } >> -- >> 2.25.1 >>