linux-kernel - [PATCH 4/8] binfmt_elf: open code copy_siginfo_to

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Date:   Tue, 14 Apr 2020 09:01:38 +0200
From:   Christoph Hellwig <hch@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     Jeremy Kerr <jk@...abs.org>, Arnd Bergmann <arnd@...db.de>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/8] binfmt_elf: open code copy_siginfo_to_user to kernelspace buffer

Instead of messing with the address limit just open code the trivial
memcpy + memset logic for the native version, and a call to
to_compat_siginfo for the compat version.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/binfmt_elf.c        | 9 +++++----
 fs/compat_binfmt_elf.c | 6 +++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 13f25e241ac4..607c5a5f855e 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1553,15 +1553,16 @@ static void fill_auxv_note(struct memelfnote *note, struct mm_struct *mm)
 	fill_note(note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
 }
 
+#ifndef fill_siginfo_note
 static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
 		const kernel_siginfo_t *siginfo)
 {
-	mm_segment_t old_fs = get_fs();
-	set_fs(KERNEL_DS);
-	copy_siginfo_to_user((user_siginfo_t __user *) csigdata, siginfo);
-	set_fs(old_fs);
+	memcpy(csigdata, siginfo, sizeof(struct kernel_siginfo));
+	memset((char *)csigdata + sizeof(struct kernel_siginfo), 0,
+		SI_EXPANSION_SIZE);
 	fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
 }
+#endif
 
 #define MAX_FILE_NOTE_SIZE (4*1024*1024)
 /*
diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index aaad4ca1217e..ab84e095618b 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c
@@ -39,7 +39,11 @@
  */
 #define user_long_t		compat_long_t
 #define user_siginfo_t		compat_siginfo_t
-#define copy_siginfo_to_user	copy_siginfo_to_user32
+#define fill_siginfo_note(note, csigdata, siginfo)		\
+do {									\
+	to_compat_siginfo(csigdata, siginfo, compat_siginfo_flags());	\
+	fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata); \
+} while (0)
 
 /*
  * The machine-dependent core note format types are defined in elfcore-compat.h,
-- 
2.25.1