From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- scripts/Makefile.kstack_erase | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 scripts/Makefile.kstack_erase (limited to 'scripts/Makefile.kstack_erase') diff --git a/scripts/Makefile.kstack_erase b/scripts/Makefile.kstack_erase new file mode 100644 index 000000000..ee7e4ef7b --- /dev/null +++ b/scripts/Makefile.kstack_erase @@ -0,0 +1,21 @@ +# SPDX-License-Identifier: GPL-2.0 + +ifdef CONFIG_GCC_PLUGIN_STACKLEAK +kstack-erase-cflags-y += -fplugin=$(objtree)/scripts/gcc-plugins/stackleak_plugin.so +kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE) +kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-arch=$(SRCARCH) +kstack-erase-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) += -fplugin-arg-stackleak_plugin-verbose +DISABLE_KSTACK_ERASE := -fplugin-arg-stackleak_plugin-disable +endif + +ifdef CONFIG_CC_IS_CLANG +kstack-erase-cflags-y += -fsanitize-coverage=stack-depth +kstack-erase-cflags-y += -fsanitize-coverage-stack-depth-callback-min=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE) +DISABLE_KSTACK_ERASE := -fno-sanitize-coverage=stack-depth +endif + +KSTACK_ERASE_CFLAGS := $(kstack-erase-cflags-y) + +export KSTACK_ERASE_CFLAGS DISABLE_KSTACK_ERASE + +KBUILD_CFLAGS += $(KSTACK_ERASE_CFLAGS) -- cgit v1.3.1