kernel/linux.git/security/apparmor/match.c, branch v6.12.80

apparmor: fix differential encoding verification

2026-03-13T16:20:48+00:00

commit 39440b137546a3aa383cfdabc605fb73811b6093 upstream. Differential encoding allows loops to be created if it is abused. To prevent this the unpack should verify that a diff-encode chain terminates. Unfortunately the differential encode verification had two bugs. 1. it conflated states that had gone through check and already been marked, with states that were currently being checked and marked. This means that loops in the current chain being verified are treated as a chain that has already been verified. 2. the order bailout on already checked states compared current chain check iterators j,k instead of using the outer loop iterator i. Meaning a step backwards in states in the current chain verification was being mistaken for moving to an already verified state. Move to a double mark scheme where already verified states get a different mark, than the current chain being kept. This enables us to also drop the backwards verification check that was the cause of the second error as any already verified state is already marked. Fixes: 031dcc8f4e84 ("apparmor: dfa add support for state differential encoding") Reported-by: Qualys Security Advisory Tested-by: Salvatore Bonaccorso Reviewed-by: Georgia Garcia Reviewed-by: Cengiz Can Signed-off-by: John Johansen Signed-off-by: Greg Kroah-Hartman

apparmor: fix missing bounds check on DEFAULT table in verify_dfa()

2026-03-13T16:20:48+00:00

commit d352873bbefa7eb39995239d0b44ccdf8aaa79a4 upstream. The verify_dfa() function only checks DEFAULT_TABLE bounds when the state is not differentially encoded. When the verification loop traverses the differential encoding chain, it reads k = DEFAULT_TABLE[j] and uses k as an array index without validation. A malformed DFA with DEFAULT_TABLE[j] >= state_count, therefore, causes both out-of-bounds reads and writes. [ 57.179855] ================================================================== [ 57.180549] BUG: KASAN: slab-out-of-bounds in verify_dfa+0x59a/0x660 [ 57.180904] Read of size 4 at addr ffff888100eadec4 by task su/993 [ 57.181554] CPU: 1 UID: 0 PID: 993 Comm: su Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy) [ 57.181558] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 57.181563] Call Trace: [ 57.181572] [ 57.181577] dump_stack_lvl+0x5e/0x80 [ 57.181596] print_report+0xc8/0x270 [ 57.181605] ? verify_dfa+0x59a/0x660 [ 57.181608] kasan_report+0x118/0x150 [ 57.181620] ? verify_dfa+0x59a/0x660 [ 57.181623] verify_dfa+0x59a/0x660 [ 57.181627] aa_dfa_unpack+0x1610/0x1740 [ 57.181629] ? __kmalloc_cache_noprof+0x1d0/0x470 [ 57.181640] unpack_pdb+0x86d/0x46b0 [ 57.181647] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181653] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181656] ? aa_unpack_nameX+0x1a8/0x300 [ 57.181659] aa_unpack+0x20b0/0x4c30 [ 57.181662] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181664] ? stack_depot_save_flags+0x33/0x700 [ 57.181681] ? kasan_save_track+0x4f/0x80 [ 57.181683] ? kasan_save_track+0x3e/0x80 [ 57.181686] ? __kasan_kmalloc+0x93/0xb0 [ 57.181688] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181693] ? aa_simple_write_to_buffer+0x54/0x130 [ 57.181697] ? policy_update+0x154/0x330 [ 57.181704] aa_replace_profiles+0x15a/0x1dd0 [ 57.181707] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181710] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181712] ? aa_loaddata_alloc+0x77/0x140 [ 57.181715] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181717] ? _copy_from_user+0x2a/0x70 [ 57.181730] policy_update+0x17a/0x330 [ 57.181733] profile_replace+0x153/0x1a0 [ 57.181735] ? rw_verify_area+0x93/0x2d0 [ 57.181740] vfs_write+0x235/0xab0 [ 57.181745] ksys_write+0xb0/0x170 [ 57.181748] do_syscall_64+0x8e/0x660 [ 57.181762] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 57.181765] RIP: 0033:0x7f6192792eb2 Remove the MATCH_FLAG_DIFF_ENCODE condition to validate all DEFAULT_TABLE entries unconditionally. Fixes: 031dcc8f4e84 ("apparmor: dfa add support for state differential encoding") Reported-by: Qualys Security Advisory Tested-by: Salvatore Bonaccorso Reviewed-by: Georgia Garcia Reviewed-by: Cengiz Can Signed-off-by: Massimiliano Pellizzer Signed-off-by: John Johansen Signed-off-by: Greg Kroah-Hartman

apparmor: fix side-effect bug in match_char() macro usage

2026-03-13T16:20:48+00:00

commit 8756b68edae37ff546c02091989a4ceab3f20abd upstream. The match_char() macro evaluates its character parameter multiple times when traversing differential encoding chains. When invoked with *str++, the string pointer advances on each iteration of the inner do-while loop, causing the DFA to check different characters at each iteration and therefore skip input characters. This results in out-of-bounds reads when the pointer advances past the input buffer boundary. [ 94.984676] ================================================================== [ 94.985301] BUG: KASAN: slab-out-of-bounds in aa_dfa_match+0x5ae/0x760 [ 94.985655] Read of size 1 at addr ffff888100342000 by task file/976 [ 94.986319] CPU: 7 UID: 1000 PID: 976 Comm: file Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy) [ 94.986322] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 94.986329] Call Trace: [ 94.986341] [ 94.986347] dump_stack_lvl+0x5e/0x80 [ 94.986374] print_report+0xc8/0x270 [ 94.986384] ? aa_dfa_match+0x5ae/0x760 [ 94.986388] kasan_report+0x118/0x150 [ 94.986401] ? aa_dfa_match+0x5ae/0x760 [ 94.986405] aa_dfa_match+0x5ae/0x760 [ 94.986408] __aa_path_perm+0x131/0x400 [ 94.986418] aa_path_perm+0x219/0x2f0 [ 94.986424] apparmor_file_open+0x345/0x570 [ 94.986431] security_file_open+0x5c/0x140 [ 94.986442] do_dentry_open+0x2f6/0x1120 [ 94.986450] vfs_open+0x38/0x2b0 [ 94.986453] ? may_open+0x1e2/0x2b0 [ 94.986466] path_openat+0x231b/0x2b30 [ 94.986469] ? __x64_sys_openat+0xf8/0x130 [ 94.986477] do_file_open+0x19d/0x360 [ 94.986487] do_sys_openat2+0x98/0x100 [ 94.986491] __x64_sys_openat+0xf8/0x130 [ 94.986499] do_syscall_64+0x8e/0x660 [ 94.986515] ? count_memcg_events+0x15f/0x3c0 [ 94.986526] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986540] ? handle_mm_fault+0x1639/0x1ef0 [ 94.986551] ? vma_start_read+0xf0/0x320 [ 94.986558] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986561] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986563] ? fpregs_assert_state_consistent+0x50/0xe0 [ 94.986572] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986574] ? arch_exit_to_user_mode_prepare+0x9/0xb0 [ 94.986587] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986588] ? irqentry_exit+0x3c/0x590 [ 94.986595] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 94.986597] RIP: 0033:0x7fda4a79c3ea Fix by extracting the character value before invoking match_char, ensuring single evaluation per outer loop. Fixes: 074c1cd798cb ("apparmor: dfa move character match into a macro") Reported-by: Qualys Security Advisory Tested-by: Salvatore Bonaccorso Reviewed-by: Georgia Garcia Reviewed-by: Cengiz Can Signed-off-by: Massimiliano Pellizzer Signed-off-by: John Johansen Signed-off-by: Greg Kroah-Hartman

apparmor: Fix & Optimize table creation from possibly unaligned memory

2026-03-04T12:20:40+00:00

[ Upstream commit 6fc367bfd4c8886e6b1742aabbd1c0bdc310db3a ] Source blob may come from userspace and might be unaligned. Try to optize the copying process by avoiding unaligned memory accesses. - Added Fixes tag - Added "Fix &" to description as this doesn't just optimize but fixes a potential unaligned memory access Fixes: e6e8bf418850d ("apparmor: fix restricted endian type warnings for dfa unpack") Signed-off-by: Helge Deller [jj: remove duplicate word "convert" in comment trigger checkpatch warning] Signed-off-by: John Johansen Signed-off-by: Sasha Levin

AppArmor: Allow apparmor to handle unaligned dfa tables

2026-03-04T12:20:40+00:00

[ Upstream commit 64802f731214a51dfe3c6c27636b3ddafd003eb0 ] The dfa tables can originate from kernel or userspace and 8-byte alignment isn't always guaranteed and as such may trigger unaligned memory accesses on various architectures. Resulting in the following [ 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 Work around it by using the get_unaligned_xx() helpers. Fixes: e6e8bf418850d ("apparmor: fix restricted endian type warnings for dfa unpack") Reported-by: John Paul Adrian Glaubitz Closes: https://github.com/sparclinux/issues/issues/30 Signed-off-by: Helge Deller Signed-off-by: John Johansen Signed-off-by: Sasha Levin

apparmor: fix loop detection used in conflicting attachment resolution

2025-08-15T10:13:59+00:00

[ Upstream commit a88db916b8c77552f49f7d9f8744095ea01a268f ] Conflicting attachment resolution is based on the number of states traversed to reach an accepting state in the attachment DFA, accounting for DFA loops traversed during the matching process. However, the loop counting logic had multiple bugs: - The inc_wb_pos macro increments both position and length, but length is supposed to saturate upon hitting buffer capacity, instead of wrapping around. - If no revisited state is found when traversing the history, is_loop would still return true, as if there was a loop found the length of the history buffer, instead of returning false and signalling that no loop was found. As a result, the adjustment step of aa_dfa_leftmatch would sometimes produce negative counts with loop- free DFAs that traversed enough states. - The iteration in the is_loop for loop is supposed to stop before i = wb->len, so the conditional should be < instead of <=. This patch fixes the above bugs as well as the following nits: - The count and size fields in struct match_workbuf were not used, so they can be removed. - The history buffer in match_workbuf semantically stores aa_state_t and not unsigned ints, even if aa_state_t is currently unsigned int. - The local variables in is_loop are counters, and thus should be unsigned ints instead of aa_state_t's. Fixes: 21f606610502 ("apparmor: improve overlapping domain attachment resolution") Signed-off-by: Ryan Lee Co-developed-by: John Johansen Signed-off-by: John Johansen Signed-off-by: Sasha Levin

apparmor: ensure WB_HISTORY_SIZE value is a power of 2

2025-08-15T10:13:59+00:00

[ Upstream commit 6c055e62560b958354625604293652753d82bcae ] WB_HISTORY_SIZE was defined to be a value not a power of 2, despite a comment in the declaration of struct match_workbuf stating it is and a modular arithmetic usage in the inc_wb_pos macro assuming that it is. Bump WB_HISTORY_SIZE's value up to 32 and add a BUILD_BUG_ON_NOT_POWER_OF_2 line to ensure that any future changes to the value of WB_HISTORY_SIZE respect this requirement. Fixes: 136db994852a ("apparmor: increase left match history buffer size") Signed-off-by: Ryan Lee Signed-off-by: John Johansen Signed-off-by: Sasha Levin

apparmor: refcount the pdb

2023-10-18T22:30:47+00:00

With the move to permission tables the dfa is no longer a stand alone entity when used, needing a minimum of a permission table. However it still could be shared among different pdbs each using a different permission table. Instead of duping the permission table when sharing a pdb, add a refcount to the pdb so it can be easily shared. Reviewed-by: Georgia Garcia Signed-off-by: John Johansen

apparmor: Fix kernel-doc warnings in apparmor/match.c

2023-07-10T08:14:51+00:00

Fix kernel-doc warnings: security/apparmor/match.c:148: warning: Function parameter or member 'tables' not described in 'verify_table_headers' security/apparmor/match.c:289: warning: Excess function parameter 'kr' description in 'aa_dfa_free_kref' security/apparmor/match.c:289: warning: Function parameter or member 'kref' not described in 'aa_dfa_free_kref' Signed-off-by: Gaosheng Cui Signed-off-by: John Johansen

apparmor: Add __init annotation to aa_{setup/teardown}_dfa_engine()

2022-11-02T04:17:26+00:00

The aa_setup_dfa_engine() and aa_teardown_dfa_engine() is only called in apparmor_init(), so let us add __init annotation to them. Fixes: 11c236b89d7c ("apparmor: add a default null dfa") Signed-off-by: Xiu Jianfeng Signed-off-by: John Johansen