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Eric Dumazet ae633388ca pptp: fix pptp_xmit() error path
I accidentally added a bug in pptp_xmit() that syzbot caught for us.

Only call ip_rt_put() if a route has been allocated.

BUG: unable to handle page fault for address: ffffffffffffffdb
PGD df3b067 P4D df3b067 PUD df3d067 PMD 0
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6346 Comm: syz.0.336 Not tainted 6.16.0-next-20250804-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:85 [inline]
RIP: 0010:raw_atomic_sub_return_release include/linux/atomic/atomic-arch-fallback.h:846 [inline]
RIP: 0010:atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:327 [inline]
RIP: 0010:__rcuref_put include/linux/rcuref.h:109 [inline]
RIP: 0010:rcuref_put+0x172/0x210 include/linux/rcuref.h:173
Call Trace:
 <TASK>
 dst_release+0x24/0x1b0 net/core/dst.c:167
 ip_rt_put include/net/route.h:285 [inline]
 pptp_xmit+0x14b/0x1a90 drivers/net/ppp/pptp.c:267
 __ppp_channel_push+0xf2/0x1c0 drivers/net/ppp/ppp_generic.c:2166
 ppp_channel_push+0x123/0x660 drivers/net/ppp/ppp_generic.c:2198
 ppp_write+0x2b0/0x400 drivers/net/ppp/ppp_generic.c:544
 vfs_write+0x27b/0xb30 fs/read_write.c:684
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: de9c4861fb ("pptp: ensure minimal skb length in pptp_xmit()")
Reported-by: syzbot+27d7cfbc93457e472e00@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/689095a5.050a0220.1fc43d.0009.GAE@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250807142146.2877060-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-08-07 07:47:04 -07:00
arch bpf-next-6.17 2025-07-30 09:58:50 -07:00
block Driver core changes for 6.17-rc1 2025-07-29 12:15:39 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Crypto library updates for 6.17 2025-07-28 17:58:52 -07:00
Documentation dt-bindings: net: Replace bouncing Alexandru Tachici emails 2025-08-05 16:00:10 -07:00
drivers pptp: fix pptp_xmit() error path 2025-08-07 07:47:04 -07:00
fs bpf-next-6.17 2025-07-30 09:58:50 -07:00
include net: Add locking to protect skb->dev access in ip_output 2025-08-01 15:17:52 -07:00
init x86/boot changes for v6.17: 2025-07-29 18:58:22 -07:00
io_uring for-6.17/io_uring-20250728 2025-07-28 16:30:12 -07:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel bpf-next-6.17 2025-07-30 09:58:50 -07:00
lib Networking changes for 6.17. 2025-07-30 08:58:55 -07:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm Summary 2025-07-29 21:43:08 -07:00
net net: Update threaded state in napi config in netif_set_threaded 2025-08-05 17:46:15 -07:00
rust Networking changes for 6.17. 2025-07-30 08:58:55 -07:00
samples Driver core changes for 6.17-rc1 2025-07-29 12:15:39 -07:00
scripts Networking changes for 6.17. 2025-07-30 08:58:55 -07:00
security powerpc updates for 6.17 2025-07-29 20:28:38 -07:00
sound A treewide cleanup of struct cycle_counter const annotations: 2025-07-29 14:02:53 -07:00
tools net: Update threaded state in napi config in netif_set_threaded 2025-08-05 17:46:15 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt KVM: Allow CPU to reschedule while setting per-page memory attributes 2025-06-24 12:20:17 -07:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore Python compiled bytecode 2025-04-24 10:12:46 -06:00
.mailmap 11 hotfixes. 9 are cc:stable and the remainder address post-6.15 issues 2025-07-24 19:13:30 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mm: update MAINTAINERS entry for HMM 2025-07-19 19:26:16 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Networking changes for 6.17. 2025-07-30 08:58:55 -07:00
Makefile hardening updates for v6.17-rc1 2025-07-28 17:16:12 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.