Revision e6838a29ecb484c97e4efef9429643b9851fba6e authored by J. Bruce Fields on 21 April 2017, 20:10:18 UTC, committed by J. Bruce Fields on 25 April 2017, 20:34:37 UTC
A client can append random data to the end of an NFSv2 or NFSv3 RPC call without our complaining; we'll just stop parsing at the end of the expected data and ignore the rest. Encoded arguments and replies are stored together in an array of pages, and if a call is too large it could leave inadequate space for the reply. This is normally OK because NFS RPC's typically have either short arguments and long replies (like READ) or long arguments and short replies (like WRITE). But a client that sends an incorrectly long reply can violate those assumptions. This was observed to cause crashes. Also, several operations increment rq_next_page in the decode routine before checking the argument size, which can leave rq_next_page pointing well past the end of the page array, causing trouble later in svc_free_pages. So, following a suggestion from Neil Brown, add a central check to enforce our expectation that no NFSv2/v3 call has both a large call and a large reply. As followup we may also want to rewrite the encoding routines to check more carefully that they aren't running off the end of the page array. We may also consider rejecting calls that have any extra garbage appended. That would be safer, and within our rights by spec, but given the age of our server and the NFS protocol, and the fact that we've never enforced this before, we may need to balance that against the possibility of breaking some oddball client. Reported-by: Tuomas Haanpää <thaan@synopsys.com> Reported-by: Ari Kauppi <ari@synopsys.com> Cc: stable@vger.kernel.org Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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Makefile
###
# scripts contains sources for various helper programs used throughout
# the kernel for the build process.
# ---------------------------------------------------------------------------
# kallsyms: Find all symbols in vmlinux
# pnmttologo: Convert pnm files to logo files
# conmakehash: Create chartable
# conmakehash: Create arrays for initializing the kernel console tables
# docproc: Used in Documentation/DocBook
# check-lc_ctype: Used in Documentation/DocBook
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-$(CONFIG_KALLSYMS) += kallsyms
hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
hostprogs-$(CONFIG_ASN1) += asn1_compiler
hostprogs-$(CONFIG_MODULE_SIG) += sign-file
hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert
hostprogs-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert
HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include
HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
HOSTLOADLIBES_sign-file = -lcrypto
HOSTLOADLIBES_extract-cert = -lcrypto
always := $(hostprogs-y) $(hostprogs-m)
# The following hostprogs-y programs are only build on demand
hostprogs-y += unifdef docproc check-lc_ctype
# These targets are used internally to avoid "is up to date" messages
PHONY += build_unifdef build_docproc build_check-lc_ctype
build_unifdef: $(obj)/unifdef
@:
build_docproc: $(obj)/docproc
@:
build_check-lc_ctype: $(obj)/check-lc_ctype
@:
subdir-$(CONFIG_MODVERSIONS) += genksyms
subdir-y += mod
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_DTC) += dtc
subdir-$(CONFIG_GDB_SCRIPTS) += gdb
# Let clean descend into subdirs
subdir- += basic kconfig package gcc-plugins
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