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Revision d6e621de1fceb3b098ebf435ef7ea91ec4838a1a authored by Phillip Lougher on 15 May 2021, 00:27:16 UTC, committed by Linus Torvalds on 15 May 2021, 02:41:32 UTC 
squashfs: fix divide error in calculate_skip()
 
Sysbot has reported a "divide error" which has been identified as being
caused by a corrupted file_size value within the file inode.  This value
has been corrupted to a much larger value than expected.

Calculate_skip() is passed i_size_read(inode) >> msblk->block_log.  Due to
the file_size value corruption this overflows the int argument/variable in
that function, leading to the divide error.

This patch changes the function to use u64.  This will accommodate any
unexpectedly large values due to corruption.

The value returned from calculate_skip() is clamped to be never more than
SQUASHFS_CACHED_BLKS - 1, or 7.  So file_size corruption does not lead to
an unexpectedly large return result here.

Link: https://lkml.kernel.org/r/20210507152618.9447-1-phillip@squashfs.org.uk
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reported-by: <syzbot+e8f781243ce16ac2f962@syzkaller.appspotmail.com>
Reported-by: <syzbot+7b98870d4fec9447b951@syzkaller.appspotmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent eb1f065
Raw File
Makefile.clean 
# SPDX-License-Identifier: GPL-2.0
# ==========================================================================
# Cleaning up
# ==========================================================================

src := $(obj)

PHONY := __clean
__clean:

include $(srctree)/scripts/Kbuild.include

# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)

# Figure out what we need to build from the various variables
# ==========================================================================

subdir-ymn := $(sort $(subdir-y) $(subdir-m) $(subdir-) \
		$(patsubst %/,%, $(filter %/, $(obj-y) $(obj-m) $(obj-))))

# Add subdir path

subdir-ymn	:= $(addprefix $(obj)/,$(subdir-ymn))

# build a list of files to remove, usually relative to the current
# directory

__clean-files	:= \
	$(clean-files) $(targets) $(hostprogs) $(userprogs) \
	$(extra-y) $(extra-m) $(extra-) \
	$(always-y) $(always-m) $(always-) \
	$(hostprogs-always-y) $(hostprogs-always-m) $(hostprogs-always-) \
	$(userprogs-always-y) $(userprogs-always-m) $(userprogs-always-)

__clean-files   := $(filter-out $(no-clean-files), $(__clean-files))

# clean-files is given relative to the current directory, unless it
# starts with $(objtree)/ (which means "./", so do not add "./" unless
# you want to delete a file from the toplevel object directory).

__clean-files   := $(wildcard                                               \
		   $(addprefix $(obj)/, $(filter-out $(objtree)/%, $(__clean-files))) \
		   $(filter $(objtree)/%, $(__clean-files)))

# ==========================================================================

quiet_cmd_clean = CLEAN   $(obj)
      cmd_clean = rm -rf $(__clean-files)

__clean: $(subdir-ymn)
ifneq ($(strip $(__clean-files)),)
	$(call cmd,clean)
endif
	@:


# ===========================================================================
# Generic stuff
# ===========================================================================

# Descending
# ---------------------------------------------------------------------------

PHONY += $(subdir-ymn)
$(subdir-ymn):
	$(Q)$(MAKE) $(clean)=$@

.PHONY: $(PHONY)
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