Revision ceb1eb2fb609c88363e06618b8d4bbf7815a4e03 authored by Tung Nguyen on 27 October 2020, 03:24:03 UTC, committed by Jakub Kicinski on 29 October 2020, 16:51:52 UTC
Commit ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") replaced skb_unshare() with skb_copy() to not reduce the data reference counter of the original skb intentionally. This is not the correct way to handle the cloned skb because it causes memory leak in 2 following cases: 1/ Sending multicast messages via broadcast link The original skb list is cloned to the local skb list for local destination. After that, the data reference counter of each skb in the original list has the value of 2. This causes each skb not to be freed after receiving ACK: tipc_link_advance_transmq() { ... /* release skb */ __skb_unlink(skb, &l->transmq); kfree_skb(skb); <-- memory exists after being freed } 2/ Sending multicast messages via replicast link Similar to the above case, each skb cannot be freed after purging the skb list: tipc_mcast_xmit() { ... __skb_queue_purge(pkts); <-- memory exists after being freed } This commit fixes this issue by using skb_unshare() instead. Besides, to avoid use-after-free error reported by KASAN, the pointer to the fragment is set to NULL before calling skb_unshare() to make sure that the original skb is not freed after freeing the fragment 2 times in case skb_unshare() returns NULL. Fixes: ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") Acked-by: Jon Maloy <jmaloy@redhat.com> Reported-by: Thang Hoang Ngo <thang.h.ngo@dektech.com.au> Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au> Reviewed-by: Xin Long <lucien.xin@gmail.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Link: https://lore.kernel.org/r/20201027032403.1823-1-tung.q.nguyen@dektech.com.au Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Kbuild
# SPDX-License-Identifier: GPL-2.0
#
# Kbuild for top-level directory of the kernel
#####
# Generate bounds.h
bounds-file := include/generated/bounds.h
always-y := $(bounds-file)
targets := kernel/bounds.s
$(bounds-file): kernel/bounds.s FORCE
$(call filechk,offsets,__LINUX_BOUNDS_H__)
#####
# Generate timeconst.h
timeconst-file := include/generated/timeconst.h
filechk_gentimeconst = echo $(CONFIG_HZ) | bc -q $<
$(timeconst-file): kernel/time/timeconst.bc FORCE
$(call filechk,gentimeconst)
#####
# Generate asm-offsets.h
offsets-file := include/generated/asm-offsets.h
always-y += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file)
$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
$(call filechk,offsets,__ASM_OFFSETS_H__)
#####
# Check for missing system calls
always-y += missing-syscalls
quiet_cmd_syscalls = CALL $<
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
$(call cmd,syscalls)
#####
# Check atomic headers are up-to-date
always-y += old-atomics
quiet_cmd_atomics = CALL $<
cmd_atomics = $(CONFIG_SHELL) $<
old-atomics: scripts/atomic/check-atomics.sh FORCE
$(call cmd,atomics)
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