In the Linux kernel, the following vulnerability has been resolved:

tcp: fix tcp_init_transfer() to not reset icsk_ca_initialized

This commit fixes a bug (found by syzkaller) that could cause spurious double-initializations for congestion control modules, which could cause memory leaks or other problems for congestion control modules (like CDG) that allocate memory in their init functions.

The buggy scenario constructed by syzkaller was something like:

(1) create a TCP socket (2) initiate a TFO connect via sendto() (3) while socket is in TCP_SYN_SENT, call setsockopt(TCP_CONGESTION), which calls: tcp_set_congestion_control() -> tcp_reinit_congestion_control() -> tcp_init_congestion_control() (4) receive ACK, connection is established, call tcp_init_transfer(), set icsk_ca_initialized=0 (without first calling cc->release()), call tcp_init_congestion_control() again.

Note that in this sequence tcp_init_congestion_control() is called twice without a cc->release() call in between. Thus, for CC modules that allocate memory in their init() function, e.g, CDG, a memory leak may occur. The syzkaller tool managed to find a reproducer that triggered such a leak in CDG.

The bug was introduced when that commit 8919a9b31eb4 ("tcp: Only init congestion control if not initialized already") introduced icsk_ca_initialized and set icsk_ca_initialized to 0 in tcp_init_transfer(), missing the possibility for a sequence like the one above, where a pro…

In the Linux kernel, the following vulnerability has been resolved:

tcp: fix tcp_init_transfer() to not reset icsk_ca_initialized

This commit fixes a bug (found by syzkaller) that could cause spurious double-initializations for congestion control modules, which could cause memory leaks or other problems for congestion control modules (like CDG) that allocate memory in their init functions.

The buggy scenario constructed by syzkaller was something like:

(1) create a TCP socket (2) initiate a TFO connect via sendto() (3) while socket is in TCP_SYN_SENT, call setsockopt(TCP_CONGESTION), which calls: tcp_set_congestion_control() -> tcp_reinit_congestion_control() -> tcp_init_congestion_control() (4) receive ACK, connection is established, call tcp_init_transfer(), set icsk_ca_initialized=0 (without first calling cc->release()), call tcp_init_congestion_control() again.

Note that in this sequence tcp_init_congestion_control() is called twice without a cc->release() call in between. Thus, for CC modules that allocate memory in their init() function, e.g, CDG, a memory leak may occur. The syzkaller tool managed to find a reproducer that triggered such a leak in CDG.

The bug was introduced when that commit 8919a9b31eb4 ("tcp: Only init congestion control if not initialized already") introduced icsk_ca_initialized and set icsk_ca_initialized to 0 in tcp_init_transfer(), missing the possibility for a sequence like the one above, where a pro…

kernel: tracing: Restructure trace_clock_global() to never block kernel: ensure definition of the fixmap area is in a limit kernel: net: ieee802154: fix null deref in parse dev addr kernel: isdn: mISDN: netjet: Fix crash in nj_probe kernel: tcp: fix tcp_init_transfer() to not reset icsk_ca_initialized kernel: irqchip/gic-v3-its: Fix potential VPE leak on error kernel: netfilter: conntrack: serialize hash resizes and cleanups kernel: userfaultfd: fix a race between writeprotect and exit_mmap() kernel: isdn: mISDN: Fix sleeping function called from invalid context kernel: mm: khugepaged: skip huge page collapse for special files kernel: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() kernel: ovl: fix warning in ovl_create_real() kernel: net/sunrpc: fix reference count leaks in rpc_sysfs_xprt_state_change kernel: i2c: mlxbf: prevent stack overflow in mlxbf_i2c_smbus_start_transaction() kernel: net: amd-xgbe: Fix skb data length underflow kernel: block: Fix wrong offset in bio_truncate() kernel: net: fix information leakage in /proc/net/ptype kernel: cifs: Fix memory leak when build ntlmssp negotiate blob failed kernel: x86/xen: Fix memory leak in xen_smp_intr_init{_pv}() kernel: Local information disclosure on Intel(R) Atom(R) processors kernel: powerpc: Fix access beyond end of drmem array kernel: efivarfs: force RO when remounting if SetVariable is not supported kernel: use-after-free in kv_parse_power_table kernel: null po…

kernel: tracing: Restructure trace_clock_global() to never block kernel: net: ieee802154: fix null deref in parse dev addr kernel: isdn: mISDN: netjet: Fix crash in nj_probe kernel: tcp: fix tcp_init_transfer() to not reset icsk_ca_initialized kernel: irqchip/gic-v3-its: Fix potential VPE leak on error kernel: netfilter: conntrack: serialize hash resizes and cleanups kernel: userfaultfd: fix a race between writeprotect and exit_mmap() kernel: isdn: mISDN: Fix sleeping function called from invalid context kernel: mm: khugepaged: skip huge page collapse for special files kernel: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() kernel: ovl: fix warning in ovl_create_real() kernel: net/sunrpc: fix reference count leaks in rpc_sysfs_xprt_state_change kernel: i2c: mlxbf: prevent stack overflow in mlxbf_i2c_smbus_start_transaction() kernel: net: amd-xgbe: Fix skb data length underflow kernel: block: Fix wrong offset in bio_truncate() kernel: net: fix information leakage in /proc/net/ptype kernel: efivarfs: force RO when remounting if SetVariable is not supported kernel: use-after-free in kv_parse_power_table kernel: null pointer dereference issues in ice_ptp.c kernel: drm: Don't unref the same fb many times by mistake due to deadlock handling kernel: wifi: mac80211: fix potential key use-after-free kernel: pstore/ram: Fix crash when setting number of cpus to an odd number kernel: ext4: avoid online resizing failures due to oversiz…

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 54 more

In the Linux kernel, the following vulnerability has been resolved: tcp: fix tcp_init_transfer() to not reset icsk_ca_initialized This commit fixes a bug (found by syzkaller) that could cause spurious double-initializations for congestion control modules, which could cause memory leaks or other problems for congestion control modules (like CDG) that allocate memory in their init functions. The buggy scenario constructed by syzkaller was something like: (1) create a TCP socket (2) initiate a TFO connect via sendto() (3) while socket is in TCP_SYN_SENT, call setsockopt(TCP_CONGESTION), which calls: tcp_set_congestion_control() -> tcp_reinit_congestion_control() -> tcp_init_congestion_control() (4) receive ACK, connection is established, call tcp_init_transfer(), set icsk_ca_initialized=0 (without first calling cc->release()), call tcp_init_congestion_control() again. Note that in this sequence tcp_init_congestion_control() is called twice without a cc->release() call in between. Thus, for CC modules that allocate memory in their init() function, e.g, CDG, a memory leak may occur. The syzkaller tool managed to find a reproducer that triggered such a leak in CDG. The bug was introduced when that commit 8919a9b31eb4 ("tcp: Only init congestion control if not initialized already") introduced icsk_ca_initialized and set icsk_ca_initialized to 0 in tcp_init_transfer(), missing the possibility for a sequence like the one above, where a process c…

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux-Kernel ausnutzen, um einen Denial-of-Service-Zustand zu erzeugen oder unspezifische Angriffe durchzuführen.