kernel/drivers/net/ppp/ppp_synctty.c, branch linux-6.18.y

net: ppp: Add bound checking for skb data on ppp_sync_txmung

2025-04-10T09:24:17Z

Ensure we have enough data in linear buffer from skb before accessing initial bytes. This prevents potential out-of-bounds accesses when processing short packets. When ppp_sync_txmung receives an incoming package with an empty payload: (remote) gef➤ p *(struct pppoe_hdr *) (skb->head + skb->network_header) $18 = { type = 0x1, ver = 0x1, code = 0x0, sid = 0x2, length = 0x0, tag = 0xffff8880371cdb96 } from the skb struct (trimmed) tail = 0x16, end = 0x140, head = 0xffff88803346f400 "4", data = 0xffff88803346f416 ":\377", truesize = 0x380, len = 0x0, data_len = 0x0, mac_len = 0xe, hdr_len = 0x0, it is not safe to access data[2]. Reported-by: syzbot+29fc8991b0ecb186cf40@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=29fc8991b0ecb186cf40 Tested-by: syzbot+29fc8991b0ecb186cf40@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Arnaud Lecomte Link: https://patch.msgid.link/20250408-bound-checking-ppp_txmung-v2-1-94bb6e1b92d0@arnaud-lcm.com [pabeni@redhat.com: fixed subj typo] Signed-off-by: Paolo Abeni

move asm/unaligned.h to linux/unaligned.h

2024-10-02T21:23:23Z

asm/unaligned.h is always an include of asm-generic/unaligned.h; might as well move that thing to linux/unaligned.h and include that - there's nothing arch-specific in that header. auto-generated by the following: for i in `git grep -l -w asm/unaligned.h`; do sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i done for i in `git grep -l -w asm-generic/unaligned.h`; do sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i done git mv include/asm-generic/unaligned.h include/linux/unaligned.h git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h

net: fill in MODULE_DESCRIPTION()s for ppp

2024-02-15T16:03:46Z

W=1 builds now warn if module is built without a MODULE_DESCRIPTION(). Add descriptions to the PPP modules. Signed-off-by: Breno Leitao Link: https://lore.kernel.org/r/20240214152741.670178-6-leitao@debian.org Signed-off-by: Jakub Kicinski

ppp: limit MRU to 64K

2023-11-13T11:09:20Z

ppp_sync_ioctl allows setting device MRU, but does not sanity check this input. Limit to a sane upper bound of 64KB. No implementation I could find generates larger than 64KB frames. RFC 2823 mentions an upper bound of PPP over SDL of 64KB based on the 16-bit length field. Other protocols will be smaller, such as PPPoE (9KB jumbo frame) and PPPoA (18190 maximum CPCS-SDU size, RFC 2364). PPTP and L2TP encapsulate in IP. Syzbot managed to trigger alloc warning in __alloc_pages: if (WARN_ON_ONCE_GFP(order > MAX_ORDER, gfp)) WARNING: CPU: 1 PID: 37 at mm/page_alloc.c:4544 __alloc_pages+0x3ab/0x4a0 mm/page_alloc.c:4544 __alloc_skb+0x12b/0x330 net/core/skbuff.c:651 __netdev_alloc_skb+0x72/0x3f0 net/core/skbuff.c:715 netdev_alloc_skb include/linux/skbuff.h:3225 [inline] dev_alloc_skb include/linux/skbuff.h:3238 [inline] ppp_sync_input drivers/net/ppp/ppp_synctty.c:669 [inline] ppp_sync_receive+0xff/0x680 drivers/net/ppp/ppp_synctty.c:334 tty_ldisc_receive_buf+0x14c/0x180 drivers/tty/tty_buffer.c:390 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:444 [inline] flush_to_ldisc+0x261/0x780 drivers/tty/tty_buffer.c:494 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 With call ioctl$PPPIOCSMRU1(r1, 0x40047452, &(0x7f0000000100)=0x5e6417a8) Similar code exists in other drivers that implement ppp_channel_ops ioctl PPPIOCSMRU. Those might also be in scope. Notably excluded from this are pppol2tp_ioctl and pppoe_ioctl. This code goes back to the start of git history. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+6177e1f90d92583bcc58@syzkaller.appspotmail.com Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

tty: Fix uninit-value access in ppp_sync_receive()

2023-11-10T11:09:53Z

KMSAN reported the following uninit-value access issue: ===================================================== BUG: KMSAN: uninit-value in ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline] BUG: KMSAN: uninit-value in ppp_sync_receive+0xdc9/0xe70 drivers/net/ppp/ppp_synctty.c:334 ppp_sync_input drivers/net/ppp/ppp_synctty.c:690 [inline] ppp_sync_receive+0xdc9/0xe70 drivers/net/ppp/ppp_synctty.c:334 tiocsti+0x328/0x450 drivers/tty/tty_io.c:2295 tty_ioctl+0x808/0x1920 drivers/tty/tty_io.c:2694 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0x211/0x400 fs/ioctl.c:857 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: __alloc_pages+0x75d/0xe80 mm/page_alloc.c:4591 __alloc_pages_node include/linux/gfp.h:238 [inline] alloc_pages_node include/linux/gfp.h:261 [inline] __page_frag_cache_refill+0x9a/0x2c0 mm/page_alloc.c:4691 page_frag_alloc_align+0x91/0x5d0 mm/page_alloc.c:4722 page_frag_alloc include/linux/gfp.h:322 [inline] __netdev_alloc_skb+0x215/0x6d0 net/core/skbuff.c:728 netdev_alloc_skb include/linux/skbuff.h:3225 [inline] dev_alloc_skb include/linux/skbuff.h:3238 [inline] ppp_sync_input drivers/net/ppp/ppp_synctty.c:669 [inline] ppp_sync_receive+0x237/0xe70 drivers/net/ppp/ppp_synctty.c:334 tiocsti+0x328/0x450 drivers/tty/tty_io.c:2295 tty_ioctl+0x808/0x1920 drivers/tty/tty_io.c:2694 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0x211/0x400 fs/ioctl.c:857 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b CPU: 0 PID: 12950 Comm: syz-executor.1 Not tainted 6.6.0-14500-g1c41041124bd #10 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 ===================================================== ppp_sync_input() checks the first 2 bytes of the data are PPP_ALLSTATIONS and PPP_UI. However, if the data length is 1 and the first byte is PPP_ALLSTATIONS, an access to an uninitialized value occurs when checking PPP_UI. This patch resolves this issue by checking the data length. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Shigeru Yoshida Reviewed-by: Simon Horman Signed-off-by: David S. Miller

tty: ldops: unify to u8

2023-08-11T19:12:47Z

Some hooks in struct tty_ldisc_ops still reference buffers by 'unsigned char'. Unify to 'u8' as the rest of the tty layer does. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: Dmitry Torokhov Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20230810091510.13006-32-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: use u8 for flags

2023-08-11T19:12:45Z

This makes all those 'char's an explicit 'u8'. This is part of the continuing unification of chars and flags to be consistent u8. This approaches tty_port_default_receive_buf(). Note that we do not change signedness as we compile with -funsigned-char. Signed-off-by: "Jiri Slaby (SUSE)" Cc: William Hubbs Cc: Chris Brannon Cc: Kirk Reiser Cc: Samuel Thibault Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: Dmitry Torokhov Cc: Arnd Bergmann Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Max Staudt Cc: Wolfgang Grandegger Cc: Marc Kleine-Budde Cc: Dario Binacchi Cc: Andreas Koensgen Cc: Jeremy Kerr Cc: Matt Johnston Cc: Krzysztof Kozlowski Cc: Liam Girdwood Cc: Mark Brown Cc: Jaroslav Kysela Cc: Takashi Iwai Acked-by: Mark Brown Link: https://lore.kernel.org/r/20230810091510.13006-18-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: use u8 for chars

2023-08-11T19:12:45Z

This makes all those 'unsigned char's an explicit 'u8'. This is part of the continuing unification of chars and flags to be consistent u8. This approaches tty_port_default_receive_buf(). Flags to be next. Signed-off-by: "Jiri Slaby (SUSE)" Cc: William Hubbs Cc: Chris Brannon Cc: Kirk Reiser Cc: Samuel Thibault Cc: Dmitry Torokhov Cc: Arnd Bergmann Cc: Max Staudt Cc: Wolfgang Grandegger Cc: Marc Kleine-Budde Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Dario Binacchi Cc: Andreas Koensgen Cc: Jeremy Kerr Cc: Matt Johnston Cc: Liam Girdwood Cc: Mark Brown Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: Peter Ujfalusi Acked-by: Mark Brown Link: https://lore.kernel.org/r/20230810091510.13006-17-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: make tty_ldisc_ops::buf() hooks operate on size_t

2023-08-11T19:12:45Z

Count passed to tty_ldisc_ops::receive_buf*(), ::lookahead_buf(), and returned from ::receive_buf2() is expected to be size_t. So set it to size_t to unify with the rest of the code. Signed-off-by: "Jiri Slaby (SUSE)" Cc: William Hubbs Cc: Chris Brannon Cc: Kirk Reiser Cc: Samuel Thibault Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: Dmitry Torokhov Cc: Arnd Bergmann Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Max Staudt Cc: Wolfgang Grandegger Cc: Marc Kleine-Budde Cc: Dario Binacchi Cc: Andreas Koensgen Cc: Jeremy Kerr Cc: Matt Johnston Cc: Krzysztof Kozlowski Cc: Liam Girdwood Cc: Mark Brown Cc: Jaroslav Kysela Cc: Takashi Iwai Acked-by: Mark Brown Link: https://lore.kernel.org/r/20230810091510.13006-16-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: remove dummy tty_ldisc_ops::poll() implementations

2023-08-11T19:12:44Z

tty_ldisc_ops::poll() is optional and needs not be provided. It is equal to returning 0. So remove all those from the code. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20230810091510.13006-4-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

kernel/drivers/net/ppp/ppp_synctty.c, branch linux-6.18.y

net: ppp: Add bound checking for skb data on ppp_sync_txmung

move asm/unaligned.h to linux/unaligned.h

net: fill in MODULE_DESCRIPTION()s for ppp

ppp: limit MRU to 64K

tty: Fix uninit-value access in ppp_sync_receive()

tty: ldops: unify to u8

tty: use u8 for flags

tty: use u8 for chars

tty: make tty_ldisc_ops::*buf*() hooks operate on size_t

tty: remove dummy tty_ldisc_ops::poll() implementations

tty: make tty_ldisc_ops::buf() hooks operate on size_t