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binfmt_elf: remove the set_fs in fill_siginfo_note

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The code in binfmt_elf.c is differnt from the rest of the code that
processes siginfo, as it sends siginfo from a kernel buffer to a file
rather than from kernel memory to userspace buffers.  To remove it's
use of set_fs the code needs some different siginfo helpers.

Add the helper copy_siginfo_to_external to copy from the kernel's
internal siginfo layout to a buffer in the siginfo layout that
userspace expects.

Modify fill_siginfo_note to use copy_siginfo_to_external instead of
set_fs and copy_siginfo_to_user.

Update compat_binfmt_elf.c to use the previously added
copy_siginfo_to_external32 to handle the compat case.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric W. Biederman 2020-05-05 12:12:54 +02:00 committed by Al Viro
parent c3b3f52476
commit fa4751f454
3 changed files with 10 additions and 5 deletions
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5
fs/binfmt_elf.c
View file

@ -1556,10 +1556,7 @@ static void fill_auxv_note(struct memelfnote *note, struct mm_struct *mm)
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);
copy_siginfo_to_external(csigdata, siginfo);
fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
}

2
fs/compat_binfmt_elf.c
View file

@ -39,7 +39,7 @@
*/
#define user_long_t compat_long_t
#define user_siginfo_t compat_siginfo_t
#define copy_siginfo_to_user copy_siginfo_to_user32
#define copy_siginfo_to_external copy_siginfo_to_external32
/*
* The machine-dependent core note format types are defined in elfcore-compat.h,

8
include/linux/signal.h
View file

@ -24,6 +24,14 @@ static inline void clear_siginfo(kernel_siginfo_t *info)
#define SI_EXPANSION_SIZE (sizeof(struct siginfo) - sizeof(struct kernel_siginfo))
static inline void copy_siginfo_to_external(siginfo_t *to,
const kernel_siginfo_t *from)
{
memcpy(to, from, sizeof(*from));
memset(((char *)to) + sizeof(struct kernel_siginfo), 0,
SI_EXPANSION_SIZE);
}
int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from);