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Wed, 31 Jan 2024 07:42:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id kjmgKPX5uWWPOgAAD6G6ig (envelope-from ); Wed, 31 Jan 2024 07:42:45 +0000 Date: Wed, 31 Jan 2024 08:42:34 +0100 From: Michal Hocko To: Oscar Salvador Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song , David Howells Subject: Re: [PATCH] fs,hugetlb: Fix NULL pointer dereference in hugetlbs_fill_super Message-ID: References: <20240130210418.3771-1-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20240130210418.3771-1-osalvador@suse.de> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5436E100021 X-Stat-Signature: 9uxmrh5rfyyoqnxt1wig83om614d33f8 X-HE-Tag: 1706686968-979542 X-HE-Meta: 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 8DgcjUjN dr9s0TYGlGuykgWqVA7KmuS8Q8Wto0SwF/HO4tNDo9+yYVNmXNVy/HurmJewnvB2bmppUkPD59mWvCAOta3wukUDKN9agaOBOThwjg4BgxNm4lcnm8qbXHrmzFZ7U6bqeVkTVO2BsQcb3D+krJAzwF+SBgK8W5BDmHPKsHoRL82YuTJgYHDHsPfhWhjpXEz0yCXMkoUTD6G7QG7vHUUjd4R/NcMM4BSHXdKBq2ZWZUp+XbrNhgdfQMmCbTJZqvPJNMPmV53nn8rMJSQcxGTx274rF8ChTALx9UDcYSjUkrX3q3xBG0S5yS8qzqH5V3MQkzOot 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 Tue 30-01-24 22:04:18, Oscar Salvador wrote: > When configuring a hugetlb filesystem via the fsconfig() syscall, there i= s a > possible NULL dereference in hugetlbfs_fill_super() caused by assigning > NULL to ctx->hstate in hugetlbfs_parse_param() when the requested pagesize > is non valid. >=20 > E.g: Taking the following steps: >=20 > fd =3D fsopen("hugetlbfs", FSOPEN_CLOEXEC); > fsconfig(fd, FSCONFIG_SET_STRING, "pagesize", "1024", 0); > fsconfig(fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); >=20 > Given that the requested "pagesize" is invalid, ctxt->hstate will be repl= aced > with NULL, losing its previous value, and we will print an error: >=20 > ... > ... > case Opt_pagesize: > ps =3D memparse(param->string, &rest); > ctx->hstate =3D h; > if (!ctx->hstate) { > pr_err("Unsupported page size %lu MB\n", ps / SZ_1M); > return -EINVAL; > } > return 0; > ... > ... >=20 > This is a problem because later on, we will dereference ctxt->hstate in > hugetlbfs_fill_super() >=20 > ... > ... > sb->s_blocksize =3D huge_page_size(ctx->hstate); > ... > ... >=20 > Causing below Oops. >=20 > Fix this by replacing cxt->hstate value only when then pagesize is known= to be valid. >=20 > kernel: hugetlbfs: Unsupported page size 0 MB > kernel: BUG: kernel NULL pointer dereference, address: 0000000000000028 > kernel: #PF: supervisor read access in kernel mode > kernel: #PF: error_code(0x0000) - not-present page > kernel: PGD 800000010f66c067 P4D 800000010f66c067 PUD 1b22f8067 PMD 0 > kernel: Oops: 0000 [#1] PREEMPT SMP PTI > kernel: CPU: 4 PID: 5659 Comm: syscall Tainted: G E 6.8.= 0-rc2-default+ #22 5a47c3fef76212addcc6eb71344aabc35190ae8f > kernel: Hardware name: Intel Corp. GROVEPORT/GROVEPORT, BIOS GVPRCRB1.86= B.0016.D04.1705030402 05/03/2017 > kernel: RIP: 0010:hugetlbfs_fill_super+0xb4/0x1a0 > kernel: Code: 48 8b 3b e8 3e c6 ed ff 48 85 c0 48 89 45 20 0f 84 d6 00 0= 0 00 48 b8 ff ff ff ff ff ff ff 7f 4c 89 e7 49 89 44 24 20 48 8b 03 <8b> 48= 28 b8 00 10 00 00 48 d3 e0 49 89 44 24 18 48 8b 03 8b 40 28 > kernel: RSP: 0018:ffffbe9960fcbd48 EFLAGS: 00010246 > kernel: RAX: 0000000000000000 RBX: ffff9af5272ae780 RCX: 0000000000372004 > kernel: RDX: ffffffffffffffff RSI: ffffffffffffffff RDI: ffff9af555e9b000 > kernel: RBP: ffff9af52ee66b00 R08: 0000000000000040 R09: 0000000000370004 > kernel: R10: ffffbe9960fcbd48 R11: 0000000000000040 R12: ffff9af555e9b000 > kernel: R13: ffffffffa66b86c0 R14: ffff9af507d2f400 R15: ffff9af507d2f400 > kernel: FS: 00007ffbc0ba4740(0000) GS:ffff9b0bd7000000(0000) knlGS:0000= 000000000000 > kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > kernel: CR2: 0000000000000028 CR3: 00000001b1ee0000 CR4: 00000000001506f0 > kernel: Call Trace: > kernel: > kernel: ? __die_body+0x1a/0x60 > kernel: ? page_fault_oops+0x16f/0x4a0 > kernel: ? search_bpf_extables+0x65/0x70 > kernel: ? fixup_exception+0x22/0x310 > kernel: ? exc_page_fault+0x69/0x150 > kernel: ? asm_exc_page_fault+0x22/0x30 > kernel: ? __pfx_hugetlbfs_fill_super+0x10/0x10 > kernel: ? hugetlbfs_fill_super+0xb4/0x1a0 > kernel: ? hugetlbfs_fill_super+0x28/0x1a0 > kernel: ? __pfx_hugetlbfs_fill_super+0x10/0x10 > kernel: vfs_get_super+0x40/0xa0 > kernel: ? __pfx_bpf_lsm_capable+0x10/0x10 > kernel: vfs_get_tree+0x25/0xd0 > kernel: vfs_cmd_create+0x64/0xe0 > kernel: __x64_sys_fsconfig+0x395/0x410 > kernel: do_syscall_64+0x80/0x160 > kernel: ? syscall_exit_to_user_mode+0x82/0x240 > kernel: ? do_syscall_64+0x8d/0x160 > kernel: ? syscall_exit_to_user_mode+0x82/0x240 > kernel: ? do_syscall_64+0x8d/0x160 > kernel: ? exc_page_fault+0x69/0x150 > kernel: entry_SYSCALL_64_after_hwframe+0x6e/0x76 > kernel: RIP: 0033:0x7ffbc0cb87c9 > kernel: Code: 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 48 89 f= 8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d= 01 f0 ff ff 73 01 c3 48 8b 0d 97 96 0d 00 f7 d8 64 89 01 48 > kernel: RSP: 002b:00007ffc29d2f388 EFLAGS: 00000206 ORIG_RAX: 0000000000= 0001af > kernel: RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ffbc0cb87c9 > kernel: RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003 > kernel: RBP: 00007ffc29d2f3b0 R08: 0000000000000000 R09: 0000000000000000 > kernel: R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 > kernel: R13: 00007ffc29d2f4c0 R14: 0000000000000000 R15: 0000000000000000 > kernel: > kernel: Modules linked in: rpcsec_gss_krb5(E) auth_rpcgss(E) nfsv4(E) dn= s_resolver(E) nfs(E) lockd(E) grace(E) sunrpc(E) netfs(E) af_packet(E) brid= ge(E) stp(E) llc(E) iscsi_ibft(E) iscsi_boot_sysfs(E) intel_rapl_msr(E) int= el_rapl_common(E) iTCO_wdt(E) intel_pmc_bxt(E) sb_edac(E) iTCO_vendor_suppo= rt(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) = rfkill(E) ipmi_ssif(E) kvm(E) acpi_ipmi(E) irqbypass(E) pcspkr(E) igb(E) ip= mi_si(E) mei_me(E) i2c_i801(E) joydev(E) intel_pch_thermal(E) i2c_smbus(E) = dca(E) lpc_ich(E) mei(E) ipmi_devintf(E) ipmi_msghandler(E) acpi_pad(E) tin= y_power_button(E) button(E) fuse(E) efi_pstore(E) configfs(E) ip_tables(E) = x_tables(E) ext4(E) mbcache(E) jbd2(E) hid_generic(E) usbhid(E) sd_mod(E) t= 10_pi(E) crct10dif_pclmul(E) crc32_pclmul(E) crc32c_intel(E) polyval_clmuln= i(E) ahci(E) xhci_pci(E) polyval_generic(E) gf128mul(E) ghash_clmulni_intel= (E) sha512_ssse3(E) sha256_ssse3(E) xhci_pci_renesas(E) libahci(E) ehci_pci= (E) sha1_ssse3(E) xhci_hcd(E) ehci_hcd(E) libata(E) > kernel: mgag200(E) i2c_algo_bit(E) usbcore(E) wmi(E) sg(E) dm_multipath= (E) dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) scsi_mod(E) sc= si_common(E) aesni_intel(E) crypto_simd(E) cryptd(E) > kernel: Unloaded tainted modules: acpi_cpufreq(E):1 fjes(E):1 > kernel: CR2: 0000000000000028 > kernel: ---[ end trace 0000000000000000 ]--- > kernel: RIP: 0010:hugetlbfs_fill_super+0xb4/0x1a0 > kernel: Code: 48 8b 3b e8 3e c6 ed ff 48 85 c0 48 89 45 20 0f 84 d6 00 0= 0 00 48 b8 ff ff ff ff ff ff ff 7f 4c 89 e7 49 89 44 24 20 48 8b 03 <8b> 48= 28 b8 00 10 00 00 48 d3 e0 49 89 44 24 18 48 8b 03 8b 40 28 > kernel: RSP: 0018:ffffbe9960fcbd48 EFLAGS: 00010246 > kernel: RAX: 0000000000000000 RBX: ffff9af5272ae780 RCX: 0000000000372004 > kernel: RDX: ffffffffffffffff RSI: ffffffffffffffff RDI: ffff9af555e9b000 > kernel: RBP: ffff9af52ee66b00 R08: 0000000000000040 R09: 0000000000370004 > kernel: R10: ffffbe9960fcbd48 R11: 0000000000000040 R12: ffff9af555e9b000 > kernel: R13: ffffffffa66b86c0 R14: ffff9af507d2f400 R15: ffff9af507d2f400 > kernel: FS: 00007ffbc0ba4740(0000) GS:ffff9b0bd7000000(0000) knlGS:0000= 000000000000 > kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > kernel: CR2: 0000000000000028 CR3: 00000001b1ee0000 CR4: 00000000001506f0 >=20 > Signed-off-by: Michal Hocko > Signed-off-by: Oscar Salvador Fixes: 32021982a324 ("hugetlbfs: Convert to fs_context") AFAICS Thanks! --=20 Michal Hocko SUSE Labs