From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
syzbot+92ead4eb8e26a26d465e@syzkaller.appspotmail.com,
Eric Biggers <ebiggers@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 5.10 38/40] crypto: af_alg - avoid undefined behavior accessing salg_name
Date: Wed, 23 Dec 2020 16:33:39 +0100 [thread overview]
Message-ID: <20201223150517.370998232@linuxfoundation.org> (raw)
In-Reply-To: <20201223150515.553836647@linuxfoundation.org>
From: Eric Biggers <ebiggers@google.com>
commit 92eb6c3060ebe3adf381fd9899451c5b047bb14d upstream.
Commit 3f69cc60768b ("crypto: af_alg - Allow arbitrarily long algorithm
names") made the kernel start accepting arbitrarily long algorithm names
in sockaddr_alg. However, the actual length of the salg_name field
stayed at the original 64 bytes.
This is broken because the kernel can access indices >= 64 in salg_name,
which is undefined behavior -- even though the memory that is accessed
is still located within the sockaddr structure. It would only be
defined behavior if the array were properly marked as arbitrary-length
(either by making it a flexible array, which is the recommended way
these days, or by making it an array of length 0 or 1).
We can't simply change salg_name into a flexible array, since that would
break source compatibility with userspace programs that embed
sockaddr_alg into another struct, or (more commonly) declare a
sockaddr_alg like 'struct sockaddr_alg sa = { .salg_name = "foo" };'.
One solution would be to change salg_name into a flexible array only
when '#ifdef __KERNEL__'. However, that would keep userspace without an
easy way to actually use the longer algorithm names.
Instead, add a new structure 'sockaddr_alg_new' that has the flexible
array field, and expose it to both userspace and the kernel.
Make the kernel use it correctly in alg_bind().
This addresses the syzbot report
"UBSAN: array-index-out-of-bounds in alg_bind"
(https://syzkaller.appspot.com/bug?extid=92ead4eb8e26a26d465e).
Reported-by: syzbot+92ead4eb8e26a26d465e@syzkaller.appspotmail.com
Fixes: 3f69cc60768b ("crypto: af_alg - Allow arbitrarily long algorithm names")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
crypto/af_alg.c | 10 +++++++---
include/uapi/linux/if_alg.h | 16 ++++++++++++++++
2 files changed, 23 insertions(+), 3 deletions(-)
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -147,7 +147,7 @@ static int alg_bind(struct socket *sock,
const u32 allowed = CRYPTO_ALG_KERN_DRIVER_ONLY;
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
- struct sockaddr_alg *sa = (void *)uaddr;
+ struct sockaddr_alg_new *sa = (void *)uaddr;
const struct af_alg_type *type;
void *private;
int err;
@@ -155,7 +155,11 @@ static int alg_bind(struct socket *sock,
if (sock->state == SS_CONNECTED)
return -EINVAL;
- if (addr_len < sizeof(*sa))
+ BUILD_BUG_ON(offsetof(struct sockaddr_alg_new, salg_name) !=
+ offsetof(struct sockaddr_alg, salg_name));
+ BUILD_BUG_ON(offsetof(struct sockaddr_alg, salg_name) != sizeof(*sa));
+
+ if (addr_len < sizeof(*sa) + 1)
return -EINVAL;
/* If caller uses non-allowed flag, return error. */
@@ -163,7 +167,7 @@ static int alg_bind(struct socket *sock,
return -EINVAL;
sa->salg_type[sizeof(sa->salg_type) - 1] = 0;
- sa->salg_name[sizeof(sa->salg_name) + addr_len - sizeof(*sa) - 1] = 0;
+ sa->salg_name[addr_len - sizeof(*sa) - 1] = 0;
type = alg_get_type(sa->salg_type);
if (PTR_ERR(type) == -ENOENT) {
--- a/include/uapi/linux/if_alg.h
+++ b/include/uapi/linux/if_alg.h
@@ -24,6 +24,22 @@ struct sockaddr_alg {
__u8 salg_name[64];
};
+/*
+ * Linux v4.12 and later removed the 64-byte limit on salg_name[]; it's now an
+ * arbitrary-length field. We had to keep the original struct above for source
+ * compatibility with existing userspace programs, though. Use the new struct
+ * below if support for very long algorithm names is needed. To do this,
+ * allocate 'sizeof(struct sockaddr_alg_new) + strlen(algname) + 1' bytes, and
+ * copy algname (including the null terminator) into salg_name.
+ */
+struct sockaddr_alg_new {
+ __u16 salg_family;
+ __u8 salg_type[14];
+ __u32 salg_feat;
+ __u32 salg_mask;
+ __u8 salg_name[];
+};
+
struct af_alg_iv {
__u32 ivlen;
__u8 iv[0];
next prev parent reply other threads:[~2020-12-23 15:35 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 15:33 [PATCH 5.10 00/40] 5.10.3-rc1 review Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 01/40] net: ipconfig: Avoid spurious blank lines in boot log Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 02/40] x86/split-lock: Avoid returning with interrupts enabled Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 03/40] exfat: Avoid allocating upcase table using kcalloc() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 04/40] soc/tegra: fuse: Fix index bug in get_process_id Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 05/40] usb: mtu3: fix memory corruption in mtu3_debugfs_regset() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 06/40] USB: serial: option: add interface-number sanity check to flag handling Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 07/40] USB: gadget: f_acm: add support for SuperSpeed Plus Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 08/40] USB: gadget: f_midi: setup SuperSpeed Plus descriptors Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 09/40] usb: gadget: f_fs: Re-use SS descriptors for SuperSpeedPlus Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 10/40] USB: gadget: f_rndis: fix bitrate for SuperSpeed and above Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 11/40] usb: chipidea: ci_hdrc_imx: Pass DISABLE_DEVICE_STREAMING flag to imx6ul Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 12/40] ARM: dts: exynos: fix roles of USB 3.0 ports on Odroid XU Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 13/40] ARM: dts: exynos: fix USB 3.0 VBUS control and over-current pins on Exynos5410 Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 14/40] ARM: dts: exynos: fix USB 3.0 pins supply being turned off on Odroid XU Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 15/40] coresight: tmc-etf: Fix NULL ptr dereference in tmc_enable_etf_sink_perf() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 16/40] coresight: tmc-etr: Check if page is valid before dma_map_page() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 17/40] coresight: tmc-etr: Fix barrier packet insertion for perf buffer Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 18/40] coresight: etb10: Fix possible NULL ptr dereference in etb_enable_perf() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 19/40] coresight: etm4x: Skip setting LPOVERRIDE bit for qcom, skip-power-up Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 20/40] coresight: etm4x: Fix accesses to TRCVMIDCTLR1 Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 21/40] coresight: etm4x: Fix accesses to TRCCIDCTLR1 Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 22/40] coresight: etm4x: Fix accesses to TRCPROCSELR Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 23/40] coresight: etm4x: Handle TRCVIPCSSCTLR accesses Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 24/40] f2fs: fix to seek incorrect data offset in inline data file Greg Kroah-Hartman
2020-12-24 1:11 ` Chao Yu
2020-12-24 7:52 ` Greg Kroah-Hartman
2020-12-24 9:38 ` Chao Yu
2020-12-23 15:33 ` [PATCH 5.10 25/40] f2fs: init dirty_secmap incorrectly Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 26/40] scsi: megaraid_sas: Check user-provided offsets Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 27/40] HID: i2c-hid: add Vero K147 to descriptor override Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 28/40] serial_core: Check for port state when tty is in error state Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 29/40] fscrypt: remove kernel-internal constants from UAPI header Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 30/40] fscrypt: add fscrypt_is_nokey_name() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 31/40] ubifs: prevent creating duplicate encrypted filenames Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 32/40] ext4: " Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 33/40] f2fs: " Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 34/40] Bluetooth: Fix slab-out-of-bounds read in hci_le_direct_adv_report_evt() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 35/40] quota: Sanity-check quota file headers on load Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 36/40] fs: quota: fix array-index-out-of-bounds bug by passing correct argument to vfs_cleanup_quota_inode() Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 37/40] media: msi2500: assign SPI bus number dynamically Greg Kroah-Hartman
2020-12-23 15:33 ` Greg Kroah-Hartman [this message]
2020-12-23 15:33 ` [PATCH 5.10 39/40] nl80211: validate key indexes for cfg80211_registered_device Greg Kroah-Hartman
2020-12-23 15:33 ` [PATCH 5.10 40/40] md: fix a warning caused by a race between concurrent md_ioctl()s Greg Kroah-Hartman
2020-12-24 0:56 ` [PATCH 5.10 00/40] 5.10.3-rc1 review Daniel Díaz
2020-12-26 15:07 ` Greg Kroah-Hartman
2020-12-24 9:43 ` Jeffrin Jose T
2020-12-26 15:06 ` Greg Kroah-Hartman
2020-12-27 15:50 ` Jeffrin Jose T
2020-12-27 16:05 ` Greg Kroah-Hartman
2020-12-27 21:33 ` Jeffrin Jose T
2020-12-28 9:50 ` Pavel Machek
2020-12-28 20:41 ` Guenter Roeck
2021-01-03 13:07 ` Jeffrin Jose T
2021-01-04 6:21 ` Greg Kroah-Hartman
2021-01-06 19:38 ` Jeffrin Jose T
2021-01-06 19:49 ` Greg Kroah-Hartman
2021-01-06 23:56 ` Jeffrin Jose T
2020-12-24 15:26 ` Guenter Roeck
2020-12-26 15:06 ` Greg Kroah-Hartman
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