[PATCH 3/5] binfmt_elf: remove the set_fs in fill_siginfo_note
From: Christoph Hellwig <hch@lst.de>
Date: 2020-04-27 20:07:03
Also in:
linux-fsdevel, lkml
Subsystem:
exec & binfmt api, elf, filesystems (vfs and infrastructure), the rest · Maintainers:
Kees Cook, Alexander Viro, Christian Brauner, Linus Torvalds
From: "Eric W. Biederman" <redacted> 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" <redacted> Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/binfmt_elf.c | 5 +---- fs/compat_binfmt_elf.c | 2 +- include/linux/signal.h | 8 ++++++++ 3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 13f25e241ac46..a1f57e20c3cf2 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c@@ -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); }
diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index aaad4ca1217ef..fa0e24e1b7267 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c@@ -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,
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 05bacd2ab1350..6bb1a3f0258c2 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h@@ -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);
--
2.26.1