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23 October 2021, 00:29:24 UTC
Revision c7b76f854e01cfdfdfaeb22b2ba1350be5d09ad7 authored by David S. Miller on 11 March 2014, 20:26:46 UTC, committed by David S. Miller on 11 March 2014, 20:26:46 UTC 
Merge branch 'skb_frags'
 
Michael S. Tsirkin says:

====================
skbuff: fix skb_segment with zero copy skbs

This fixes a bug in skb_segment where it moves frags
between skbs without orphaning them.
This causes userspace to assume it's safe to
reuse the buffer, and receiver gets corrupted data.
This further might leak information from the
transmitter on the wire.

To fix track which skb does a copied frag belong
to, and orphan frags when copying them.

As we are tracking multiple skbs here, using
short names (skb,nskb,fskb,skb_frag,frag) becomes confusing.
So before adding another one, I refactor these names
slightly.

Patch is split out to make it easier to
verify that all trasformations are trivially correct.

The problem was observed in the field,
so I think that the patch is necessary on stable
as well.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
2 parent s 9d79b3c + 1fd819e
Raw File
Tip revision: c7b76f854e01cfdfdfaeb22b2ba1350be5d09ad7 authored by David S. Miller on 11 March 2014, 20:26:46 UTC
Merge branch 'skb_frags'
Tip revision: c7b76f8
Kbuild 
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate bounds.h
# 2) Generate asm-offsets.h (may need bounds.h)
# 3) Check for missing system calls

#####
# 1) Generate bounds.h

bounds-file := include/generated/bounds.h

always  := $(bounds-file)
targets := $(bounds-file) kernel/bounds.s

quiet_cmd_bounds = GEN     $@
define cmd_bounds
	(set -e; \
	 echo "#ifndef __LINUX_BOUNDS_H__"; \
	 echo "#define __LINUX_BOUNDS_H__"; \
	 echo "/*"; \
	 echo " * DO NOT MODIFY."; \
	 echo " *"; \
	 echo " * This file was generated by Kbuild"; \
	 echo " *"; \
	 echo " */"; \
	 echo ""; \
	 sed -ne $(sed-y) $<; \
	 echo ""; \
	 echo "#endif" ) > $@
endef

# We use internal kbuild rules to avoid the "is up to date" message from make
kernel/bounds.s: kernel/bounds.c FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(bounds-file): kernel/bounds.s Kbuild
	$(Q)mkdir -p $(dir $@)
	$(call cmd,bounds)

#####
# 2) Generate asm-offsets.h
#

offsets-file := include/generated/asm-offsets.h

always  += $(offsets-file)
targets += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s


# Default sed regexp - multiline due to syntax constraints
define sed-y
	"/^->/{s:->#\(.*\):/* \1 */:; \
	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
	s:->::; p;}"
endef

quiet_cmd_offsets = GEN     $@
define cmd_offsets
	(set -e; \
	 echo "#ifndef __ASM_OFFSETS_H__"; \
	 echo "#define __ASM_OFFSETS_H__"; \
	 echo "/*"; \
	 echo " * DO NOT MODIFY."; \
	 echo " *"; \
	 echo " * This file was generated by Kbuild"; \
	 echo " *"; \
	 echo " */"; \
	 echo ""; \
	 sed -ne $(sed-y) $<; \
	 echo ""; \
	 echo "#endif" ) > $@
endef

# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
                                      $(obj)/$(bounds-file) FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
	$(call cmd,offsets)

#####
# 3) Check for missing system calls
#

always += missing-syscalls
targets += 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)

# Keep these two files during make clean
no-clean-files := $(bounds-file) $(offsets-file)
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