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References: <20241204075248.384215-1-hao.ge@linux.dev> <20241204083448.387862-1-hao.ge@linux.dev> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 4 Dec 2024 11:33:09 -0800 Message-ID: Subject: Re: [PATCH v2] mm/alloc_tag: fix vm_module_tags_populate's KASAN poisoning logic To: Hao Ge Cc: kent.overstreet@linux.dev, akpm@linux-foundation.org, 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-Server: rspam04 X-Rspamd-Queue-Id: 7ADE340017 X-Stat-Signature: tsri5bby5kjtoa8r4ydq4ycftn9mrrxd X-Rspam-User: X-HE-Tag: 1733340787-372102 X-HE-Meta: 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 PidD58f2 jAvftJjBbEWvAjxD6EEnPS8OAcseSk11N+qlFE6dsjHbyMbn7xuHB7F+y3TT+5pG9gR2NpZyaROjO4DmNQWboytWZ3TAY4MF9m/Ws+X07DiukGQciGnbIh9S9scTiRp6mh0YNdtn+8gbKEgWCxT6k39FoVOg0t0AYmA8FjPMyars5Kg3uValluUwP0skW7UxN8dB+ysUuGx0/FNAwl7EO3Lp2e3ZYiQjdqTPvt75I89m8Eck= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Wed, Dec 4, 2024 at 7:08=E2=80=AFAM Hao Ge wrote: > > Hi Suren > > > Thank you for your review. > > > On 12/4/24 22:39, Suren Baghdasaryan wrote: > > On Wed, Dec 4, 2024 at 12:35=E2=80=AFAM Hao Ge wrote= : > >> From: Hao Ge > >> > >> After merge commit 233e89322cbe ("alloc_tag: > >> fix module allocation tags populated area calculation"), > >> We still encountered a KASAN bug. > >> > >> This is because we have only actually performed > >> page allocation and address mapping here. > >> we need to unpoisoned portions of underlying memory. > >> > >> Because we have a change in the size here,we need to > >> re-annotate poisoned and unpoisoned portions of underlying memory > >> according to the new size. > >> > >> Here is the log for KASAN: > >> > >> [ 5.041171][ T1] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D > >> [ 5.042047][ T1] BUG: KASAN: vmalloc-out-of-bounds in move_modul= e+0x2c0/0x708 > >> [ 5.042723][ T1] Write of size 240 at addr ffff80007e510000 by t= ask systemd/1 > >> [ 5.043412][ T1] > >> [ 5.043523][ T72] input: QEMU QEMU USB Tablet as /devices/pci0000= :00/0000:00:01.1/0000:02:001 > >> [ 5.043614][ T1] CPU: 0 UID: 0 PID: 1 Comm: systemd Not tainted = 6.13.0-rc1+ #28 > >> [ 5.045560][ T1] Hardware name: QEMU KVM Virtual Machine, BIOS 0= .0.0 02/06/2015 > >> [ 5.046328][ T1] Call trace: > >> [ 5.046670][ T1] show_stack+0x20/0x38 (C) > >> [ 5.047127][ T1] dump_stack_lvl+0x80/0xf8 > >> [ 5.047533][ T1] print_address_description.constprop.0+0x58/0x3= 58 > >> [ 5.048092][ T72] hid-generic 0003:0627:0001.0001: input,hidraw0:= USB HID v0.01 Mouse [QEMU 0 > >> [ 5.048126][ T1] print_report+0xb0/0x280 > >> [ 5.049682][ T1] kasan_report+0xb8/0x108 > >> [ 5.050170][ T1] kasan_check_range+0xe8/0x190 > >> [ 5.050685][ T1] memcpy+0x58/0xa0 > >> [ 5.051135][ T1] move_module+0x2c0/0x708 > >> [ 5.051586][ T1] layout_and_allocate.constprop.0+0x308/0x5b8 > >> [ 5.052219][ T1] load_module+0x134/0x16c8 > >> [ 5.052671][ T1] init_module_from_file+0xdc/0x138 > >> [ 5.053193][ T1] idempotent_init_module+0x344/0x600 > >> [ 5.053742][ T1] __arm64_sys_finit_module+0xbc/0x150 > >> [ 5.054289][ T1] invoke_syscall+0xd4/0x258 > >> [ 5.054749][ T1] el0_svc_common.constprop.0+0xb4/0x240 > >> [ 5.055319][ T1] do_el0_svc+0x48/0x68 > >> [ 5.055743][ T1] el0_svc+0x40/0xe0 > >> [ 5.056142][ T1] el0t_64_sync_handler+0x10c/0x138 > >> [ 5.056658][ T1] el0t_64_sync+0x1ac/0x1b0 > >> > >> Fixes: 233e89322cbe ("alloc_tag: fix module allocation tags populated = area calculation") > >> Signed-off-by: Hao Ge > > Thanks for the fix! > > > >> --- > >> v2: Add comments to kasan_unpoison_vmalloc like other places. > >> > >> 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 | 13 +++++++++++++ > >> 1 file changed, 13 insertions(+) > >> > >> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c > >> index 4ee6caa6d2da..f885b3f3af0e 100644 > >> --- a/lib/alloc_tag.c > >> +++ b/lib/alloc_tag.c > >> @@ -421,7 +421,20 @@ static int vm_module_tags_populate(void) > >> __free_page(next_page[i]); > >> return -ENOMEM; > >> } > >> + > >> + kasan_poison_vmalloc((void *)module_tags.start_addr, > >> + vm_module_tags->nr_pages << PAGE_= SHIFT); > >> + > >> vm_module_tags->nr_pages +=3D nr; > >> + > >> + /* > >> + * Mark the pages as accessible, now that they are map= ped. > >> + * With hardware tag-based KASAN, marking is skipped f= or > >> + * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc= (). > >> + */ > >> + kasan_unpoison_vmalloc((void *)module_tags.start_addr, > >> + vm_module_tags->nr_pages << PAG= E_SHIFT, > >> + KASAN_VMALLOC_PROT_NORMAL); > > Instead of poisoning [module_tags.start_addr, > > vm_module_tags->nr_pages], incrementing vm_module_tags->nr_pages and > > the unpoisoning [module_tags.start_addr, vm_module_tags->nr_pages] > > could we simply poisons the additional area like this: > > > > kasan_unpoison_vmalloc((void *)module_tags.start_addr = + > > (vm_module_tags->nr_pages << PA= GE_SHIFT), > > nr << PAGE_SHIFT, > > KASAN_VMALLOC_PROT_NORMAL); > > vm_module_tags->nr_pages +=3D nr; > > ? > > > I had considered making such modifications earlier. > > But considering the following situation, > > A module tags spans across the regions of [module_tags.start_addr, > vm_module_tags->nr_pages] and [module_tags.start_addr + > vm_module_tags->nr_pages, ...]. > > It may result in false positives for out-of-bounds errors. Sorry, maybe I'm missing something but I don't see why poisoning only newly mapped area would lead to false positives. Could you please clarify? Also, if you do need to unpoison and then poison, using phys_end and new_end would be better, like this: kasan_poison_vmalloc((void *)module_tags.start_addr, phys_end - module_tags.start_addr) kasan_unpoison_vmalloc((void *)module_tags.start_addr, new_end - module_tags.start_addr, KASAN_VMALLOC_PROT_NORMAL); > > > >> } > >> > >> return 0; > >> -- > >> 2.25.1 > >>