Re: [PATCH 0/2] apparmor unaligned memory fixes

John Paul Adrian Glaubitz
2025-11-18T11:43:33Z

Hi Helge,

On Tue, 2025-11-18 at 12:09 +0100, Helge Deller wrote:
> My patch fixed two call sites, but I suspect you see another call site which
> hasn't been fixed yet.
>
> Can you try attached patch? It might indicate the caller of the function and
> maybe prints the struct name/address which isn't aligned.
>
> Helge
>
>
> diff --git a/security/apparmor/match.c b/security/apparmor/match.c
> index c5a91600842a..b477430c07eb 100644
> --- a/security/apparmor/match.c
> +++ b/security/apparmor/match.c
> @@ -313,6 +313,9 @@ struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
> if (size < sizeof(struct table_set_header))
> goto fail;
>
> + if (WARN_ON(((unsigned long)data) & (BITS_PER_LONG/8 - 1)))
> + pr_warn("dfa blob stream %pS not aligned.\n", data);
> +
> if (ntohl(*(__be32 *) data) != YYTH_MAGIC)
> goto fail;

Here is the relevant output with the patch applied:

[ 73.840639] ------------[ cut here ]------------
[ 73.901376] WARNING: CPU: 0 PID: 341 at security/apparmor/match.c:316 aa_dfa_unpack+0x6cc/0x720
[ 74.015867] Modules linked in: binfmt_misc evdev flash sg drm drm_panel_orientation_quirks backlight i2c_core configfs nfnetlink autofs4 ext4 crc16 mbcache jbd2 hid_generic usbhid sr_mod hid cdrom
sd_mod ata_generic ohci_pci ehci_pci ehci_hcd ohci_hcd pata_ali libata sym53c8xx scsi_transport_spi tg3 scsi_mod usbcore libphy scsi_common mdio_bus usb_common
[ 74.428977] CPU: 0 UID: 0 PID: 341 Comm: apparmor_parser Not tainted 6.18.0-rc6+ #9 NONE
[ 74.536543] Call Trace:
[ 74.568561] [<0000000000434c24>] dump_stack+0x8/0x18
[ 74.633757] [<0000000000476438>] __warn+0xd8/0x100
[ 74.696664] [<00000000004296d4>] warn_slowpath_fmt+0x34/0x74
[ 74.771006] [<00000000008db28c>] aa_dfa_unpack+0x6cc/0x720
[ 74.843062] [<00000000008e643c>] unpack_pdb+0xbc/0x7e0
[ 74.910545] [<00000000008e7740>] unpack_profile+0xbe0/0x1300
[ 74.984888] [<00000000008e82e0>] aa_unpack+0xe0/0x6a0
[ 75.051226] [<00000000008e3ec4>] aa_replace_profiles+0x64/0x1160
[ 75.130144] [<00000000008d4d90>] policy_update+0xf0/0x280
[ 75.201057] [<00000000008d4fc8>] profile_replace+0xa8/0x100
[ 75.274258] [<0000000000766bd0>] vfs_write+0x90/0x420
[ 75.340594] [<00000000007670cc>] ksys_write+0x4c/0xe0
[ 75.406932] [<0000000000767174>] sys_write+0x14/0x40
[ 75.472126] [<0000000000406174>] linux_sparc_syscall+0x34/0x44
[ 75.548802] ---[ end trace 0000000000000000 ]---
[ 75.609503] dfa blob stream 0xfff0000008926b96 not aligned.
[ 75.682695] Kernel unaligned access at TPC[8db2a8] aa_dfa_unpack+0x6e8/0x720
[ 75.775337] Kernel unaligned access at TPC[8dac18] aa_dfa_unpack+0x58/0x720
[ 75.866840] Kernel unaligned access at TPC[8dad00] aa_dfa_unpack+0x140/0x720
[ 75.959481] Kernel unaligned access at TPC[8dad00] aa_dfa_unpack+0x140/0x720
[ 76.052125] Kernel unaligned access at TPC[8dad00] aa_dfa_unpack+0x140/0x720
[ 76.146188] ------------[ cut here ]------------
[ 76.206858] WARNING: CPU: 0 PID: 341 at security/apparmor/match.c:316 aa_dfa_unpack+0x6cc/0x720
[ 76.321326] Modules linked in: binfmt_misc evdev flash sg drm drm_panel_orientation_quirks backlight i2c_core configfs nfnetlink autofs4 ext4 crc16 mbcache jbd2 hid_generic usbhid sr_mod hid cdrom
sd_mod ata_generic ohci_pci ehci_pci ehci_hcd ohci_hcd pata_ali libata sym53c8xx scsi_transport_spi tg3 scsi_mod usbcore libphy scsi_common mdio_bus usb_common
[ 76.734360] CPU: 0 UID: 0 PID: 341 Comm: apparmor_parser Tainted: G W 6.18.0-rc6+ #9 NONE
[ 76.862518] Tainted: [W]=WARN
[ 76.901396] Call Trace:
[ 76.933421] [<0000000000434c24>] dump_stack+0x8/0x18
[ 76.998616] [<0000000000476438>] __warn+0xd8/0x100
[ 77.061522] [<00000000004296d4>] warn_slowpath_fmt+0x34/0x74
[ 77.135867] [<00000000008db28c>] aa_dfa_unpack+0x6cc/0x720
[ 77.207923] [<00000000008e643c>] unpack_pdb+0xbc/0x7e0
[ 77.275405] [<00000000008e71dc>] unpack_profile+0x67c/0x1300
[ 77.349749] [<00000000008e82e0>] aa_unpack+0xe0/0x6a0
[ 77.416084] [<00000000008e3ec4>] aa_replace_profiles+0x64/0x1160
[ 77.495003] [<00000000008d4d90>] policy_update+0xf0/0x280
[ 77.565915] [<00000000008d4fc8>] profile_replace+0xa8/0x100
[ 77.639116] [<0000000000766bd0>] vfs_write+0x90/0x420
[ 77.705454] [<00000000007670cc>] ksys_write+0x4c/0xe0
[ 77.771792] [<0000000000767174>] sys_write+0x14/0x40
[ 77.836986] [<0000000000406174>] linux_sparc_syscall+0x34/0x44
[ 77.913633] ---[ end trace 0000000000000000 ]---

The message is repeated multiple times.

Adrian

--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
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