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<20241018152925.138341-1-hao.ge@linux.dev> <20241020070819.307944-1-hao.ge@linux.dev> In-Reply-To: <20241020070819.307944-1-hao.ge@linux.dev> From: Suren Baghdasaryan Date: Mon, 21 Oct 2024 11:11:21 -0700 Message-ID: Subject: Re: [PATCH v3] mm/codetag: fix null pointer check logic for ref and tag To: Hao Ge Cc: kent.overstreet@linux.dev, akpm@linux-foundation.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Ge Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 86F86160007 X-Stat-Signature: jzohtukt4ufj67gxhr1t4a7fjrr3w1ee X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1729534283-596224 X-HE-Meta: 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 YsQ6wTXU XCDIV02/HTbWCv84cewvyAz++YfujsTjv74O7DqDL77u1i1qtYwSeE+Rsl7FoWpnmOhit95RW797o/gLTpwyK4f2vCdbNsYPy3UQfqdG58k3gHacBWpxnSTgqe9fKrZI+mu4jELbKrlHOaAWtvq/Z8FstaIVQs1ZpdQ1uNvGDOXOtOEpzIwGw4taxR+y9LDKeLGwORrQrUP46BBW2xsowjQoJDA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Oct 20, 2024 at 12:08=E2=80=AFAM 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 fix null pointer check logic for ref > and tag to avoid panic caused by a null pointer dereference. > > Here is the log for the panic: > > [ 74.779373][ T2158] Unable to handle kernel NULL pointer dereference a= t virtual address 0000000000000020 > [ 74.780130][ T2158] Mem abort info: > [ 74.780406][ T2158] ESR =3D 0x0000000096000004 > [ 74.780756][ T2158] EC =3D 0x25: DABT (current EL), IL =3D 32 bits > [ 74.781225][ T2158] SET =3D 0, FnV =3D 0 > [ 74.781529][ T2158] EA =3D 0, S1PTW =3D 0 > [ 74.781836][ T2158] FSC =3D 0x04: level 0 translation fault > [ 74.782288][ T2158] Data abort info: > [ 74.782577][ T2158] ISV =3D 0, ISS =3D 0x00000004, ISS2 =3D 0x000000= 00 > [ 74.783068][ T2158] CM =3D 0, WnR =3D 0, TnD =3D 0, TagAccess =3D 0 > [ 74.783533][ T2158] GCS =3D 0, Overlay =3D 0, DirtyBit =3D 0, Xs =3D= 0 > [ 74.784010][ T2158] user pgtable: 4k pages, 48-bit VAs, pgdp=3D0000000= 105f34000 > [ 74.784586][ T2158] [0000000000000020] pgd=3D0000000000000000, p4d=3D0= 000000000000000 > [ 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_n= at ebtable_broute ip6table_nat ip6table_mangle 4 > [ 74.790661][ T2158] CPU: 0 UID: 0 PID: 2158 Comm: kunit_try_catch Kdum= p: loaded Tainted: G W N 6.12.0-rc3+ #2 > [ 74.791535][ T2158] Tainted: [W]=3DWARN, [N]=3DTEST > [ 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 -S= SBS BTYPE=3D--) > [ 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: 0= 000000000000000 > [ 74.795095][ T2158] x26: 0000000000000000 x25: 0000000000000012 x24: f= fff80007b30e314 > [ 74.795822][ T2158] x23: ffff000390ff6f10 x22: 0000000000000000 x21: 0= 000000000000088 > [ 74.796555][ T2158] x20: ffff000390285840 x19: fffffd7fc3ef7830 x18: f= fffffffffffffff > [ 74.797283][ T2158] x17: ffff8000800e63b4 x16: ffff80007b33afc4 x15: f= fff800081654c00 > [ 74.798011][ T2158] x14: 0000000000000000 x13: 205d383531325420 x12: 5= b5d383734363537 > [ 74.798744][ T2158] x11: ffff800084d337e0 x10: 000000000000005d x9 : 0= 0000000ffffffd0 > [ 74.799476][ T2158] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008219d188 x6 : c= 0000000ffff7fff > [ 74.800206][ T2158] x5 : ffff0003fdbc9208 x4 : ffff800081edd188 x3 : 0= 000000000000001 > [ 74.800932][ T2158] x2 : 0beaa6dee1ac5a00 x1 : 0beaa6dee1ac5a00 x0 : f= fff80037c2cb000 > [ 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_kuni= t] > [ 74.803607][ T2158] kunit_try_run_case+0x70/0x17c [kunit] > [ 74.804124][ T2158] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kun= it] > [ 74.804768][ T2158] kthread+0x10c/0x118 > [ 74.805141][ T2158] ret_from_fork+0x10/0x20 > [ 74.805540][ T2158] Code: b9400a80 11000400 b9000a80 97ffd858 (f94012d= 3) > [ 74.806176][ T2158] SMP: stopping secondary CPUs > [ 74.808130][ T2158] Starting crashdump kernel... > > Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") > Suggested-by: Suren Baghdasaryan > Acked-by: Yu Zhao > Signed-off-by: Hao Ge Thanks for the fix! Acked-by: Suren Baghdasaryan > --- > v3: Modify the code logic based on Suren's suggestions. > Update title and commit message due to code logic change. > Add Suggested-by: Suren Baghdasaryan > Add Acked-by: Yu Zhao > > 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 | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h > index 1f0a9ff23a2c..941deffc590d 100644 > --- a/include/linux/alloc_tag.h > +++ b/include/linux/alloc_tag.h > @@ -135,18 +135,21 @@ static inline void alloc_tag_sub_check(union codeta= g_ref *ref) {} > #endif > > /* Caller should verify both ref and tag to be valid */ > -static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct al= loc_tag *tag) > +static inline bool __alloc_tag_ref_set(union codetag_ref *ref, struct al= loc_tag *tag) > { > alloc_tag_add_check(ref, tag); > if (!ref || !tag) > - return; > + return false; > > ref->ct =3D &tag->ct; > + return true; > } > > -static inline void alloc_tag_ref_set(union codetag_ref *ref, struct allo= c_tag *tag) > +static inline bool alloc_tag_ref_set(union codetag_ref *ref, struct allo= c_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 on= es. > @@ -154,12 +157,13 @@ static inline void alloc_tag_ref_set(union codetag_= ref *ref, struct alloc_tag *t > * counter because when we free each part the counter will be dec= remented. > */ > this_cpu_inc(tag->counters->calls); > + return true; > } > > static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_ta= g *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); > } > > static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes) > -- > 2.25.1 >