| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250901135350.619485-1-svetlana.parfenova@syntacore.com>
Date: Mon, 1 Sep 2025 20:53:50 +0700
From: Svetlana Parfenova <svetlana.parfenova@...tacore.com>
To: <linux-fsdevel@...r.kernel.org>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>, <linux-riscv@...ts.infradead.org>
CC: <paul.walmsley@...ive.com>, <palmer@...belt.com>, <aou@...s.berkeley.edu>,
<alex@...ti.f>, <viro@...iv.linux.org.uk>, <brauner@...nel.org>,
<jack@...e.cz>, <kees@...nel.org>, <akpm@...ux-foundation.org>,
<david@...hat.com>, <lorenzo.stoakes@...cle.com>, <Liam.Howlett@...cle.com>,
<vbabka@...e.cz>, <rppt@...nel.org>, <surenb@...gle.com>, <mhocko@...e.com>,
<svetlana.parfenova@...tacore.com>
Subject: [RFC RESEND v3] binfmt_elf: preserve original ELF e_flags for core dumps
Some architectures, such as RISC-V, use the ELF e_flags field to encode
ABI-specific information (e.g., ISA extensions, fpu support). Debuggers
like GDB rely on these flags in core dumps to correctly interpret
optional register sets. If the flags are missing or incorrect, GDB may
warn and ignore valid data, for example:
warning: Unexpected size of section '.reg2/213' in core file.
This can prevent access to fpu or other architecture-specific registers
even when they were dumped.
Save the e_flags field during ELF binary loading (in load_elf_binary())
into the mm_struct, and later retrieve it during core dump generation
(in fill_note_info()). Kconfig option CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
is introduced for architectures that require this behaviour.
Signed-off-by: Svetlana Parfenova <svetlana.parfenova@...tacore.com>
---
Changes in v3:
- Introduce CONFIG_ARCH_HAS_ELF_CORE_EFLAGS Kconfig option instead of
arch-specific ELF_CORE_USE_PROCESS_EFLAGS define.
- Add helper functions to set/get e_flags in mm_struct.
- Wrap saved_e_flags field of mm_struct with
#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS.
Changes in v2:
- Remove usage of Kconfig option.
- Add an architecture-optional macro to set process e_flags. Enabled
by defining ELF_CORE_USE_PROCESS_EFLAGS. Defaults to no-op if not
used.
arch/riscv/Kconfig | 1 +
fs/Kconfig.binfmt | 9 +++++++++
fs/binfmt_elf.c | 40 ++++++++++++++++++++++++++++++++++------
include/linux/mm_types.h | 5 +++++
4 files changed, 49 insertions(+), 6 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a4b233a0659e..1bef00208bdd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -224,6 +224,7 @@ config RISCV
select VDSO_GETRANDOM if HAVE_GENERIC_VDSO
select USER_STACKTRACE_SUPPORT
select ZONE_DMA32 if 64BIT
+ select ARCH_HAS_ELF_CORE_EFLAGS
config RUSTC_SUPPORTS_RISCV
def_bool y
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index bd2f530e5740..1949e25c7741 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -184,4 +184,13 @@ config EXEC_KUNIT_TEST
This builds the exec KUnit tests, which tests boundary conditions
of various aspects of the exec internals.
+config ARCH_HAS_ELF_CORE_EFLAGS
+ bool
+ depends on BINFMT_ELF && ELF_CORE
+ default n
+ help
+ Select this option if the architecture makes use of the e_flags
+ field in the ELF header to store ABI or other architecture-specific
+ information that should be preserved in core dumps.
+
endmenu
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 4aacf9c9cc2d..e4653bb99946 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -103,6 +103,21 @@ static struct linux_binfmt elf_format = {
#define BAD_ADDR(x) (unlikely((unsigned long)(x) >= TASK_SIZE))
+static inline void elf_coredump_set_mm_eflags(struct mm_struct *mm, u32 flags)
+{
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+ mm->saved_e_flags = flags;
+#endif
+}
+
+static inline u32 elf_coredump_get_mm_eflags(struct mm_struct *mm, u32 flags)
+{
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+ flags = mm->saved_e_flags;
+#endif
+ return flags;
+}
+
/*
* We need to explicitly zero any trailing portion of the page that follows
* p_filesz when it ends before the page ends (e.g. bss), otherwise this
@@ -1290,6 +1305,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
mm->end_data = end_data;
mm->start_stack = bprm->p;
+ elf_coredump_set_mm_eflags(mm, elf_ex->e_flags);
+
/**
* DOC: "brk" handling
*
@@ -1804,6 +1821,8 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
struct elf_thread_core_info *t;
struct elf_prpsinfo *psinfo;
struct core_thread *ct;
+ u16 machine;
+ u32 flags;
psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
if (!psinfo)
@@ -1831,17 +1850,26 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
return 0;
}
- /*
- * Initialize the ELF file header.
- */
- fill_elf_header(elf, phdrs,
- view->e_machine, view->e_flags);
+ machine = view->e_machine;
+ flags = view->e_flags;
#else
view = NULL;
info->thread_notes = 2;
- fill_elf_header(elf, phdrs, ELF_ARCH, ELF_CORE_EFLAGS);
+ machine = ELF_ARCH;
+ flags = ELF_CORE_EFLAGS;
#endif
+ /*
+ * Override ELF e_flags with value taken from process,
+ * if arch needs that.
+ */
+ flags = elf_coredump_get_mm_eflags(dump_task->mm, flags);
+
+ /*
+ * Initialize the ELF file header.
+ */
+ fill_elf_header(elf, phdrs, machine, flags);
+
/*
* Allocate a structure for each thread.
*/
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 08bc2442db93..04a2857f12f2 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1102,6 +1102,11 @@ struct mm_struct {
unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
+#ifdef CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
+ /* the ABI-related flags from the ELF header. Used for core dump */
+ unsigned long saved_e_flags;
+#endif
+
struct percpu_counter rss_stat[NR_MM_COUNTERS];
struct linux_binfmt *binfmt;
--
2.51.0
Powered by blists - more mailing lists