Revision faf309009e2e18d30c032b7d9479f29b91677c37 authored by Linus Torvalds on 22 February 2012, 01:24:20 UTC, committed by Linus Torvalds on 22 February 2012, 01:24:20 UTC
The 'poll()' system call timeout parameter is supposed to be 'int', not 'long'. Now, the reason this matters is that right now 32-bit compat mode is broken on at least x86-64, because the 32-bit code just calls 'sys_poll()' directly on x86-64, and the 32-bit argument will have been zero-extended, turning a signed 'int' into a large unsigned 'long' value. We could just introduce a 'compat_sys_poll()' function for this, and that may eventually be what we have to do, but since the actual standard poll() semantics is *supposed* to be 'int', and since at least on x86-64 glibc sign-extends the argument before invocing the system call (so nobody can actually use a 64-bit timeout value in user space _anyway_, even in 64-bit binaries), the simpler solution would seem to be to just fix the definition of the system call to match what it should have been from the very start. If it turns out that somebody somehow circumvents the user-level libc 64-bit sign extension and actually uses a large unsigned 64-bit timeout despite that not being how poll() is supposed to work, we will need to do the compat_sys_poll() approach. Reported-by: Thomas Meyer <thomas@m3y3r.de> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 797a796
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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