| Message ID | CAJ2CSBteCm19_DKfastsxAR0chQGRzAZOjPjs0Nw-ySsyCk1YA@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On 21 February 2012 10:42, Damian, Alexandru <alexandru.damian@intel.com> wrote: > Hi, > > I got a problem with QEMU refusing to load an ELF binary with 0-length > sections, > while the kernel has no issue doing this. > > This patch adds a check that has been in kernel since 2008 at least. CC'ing Riku (linux-user maintainer). > > Cheers, > Alex > > ---------------- > commit a42e5231c1be5f09caeb6c73e34933cd7efa7023 > Author: Alexandru DAMIAN <alexandru.damian@intel.com> > Date: Tue Feb 21 12:34:36 2012 +0200 > > Do not attempt to map 0-length sections > > Mmap will return an invalid argument, but 0-length sections > are valid in any case. The kernel as a similar check > when loading elf binaries courtesy of jkosina@suse.cz. > > Signed-off-by: Alexandru Damian <alexandru.damian@intel.com> Convention is to submit patches as git-format-patch style emails. > diff --git a/linux-user/elfload.c b/linux-user/elfload.c > index ea61d0d..71d0ae3 100644 > --- a/linux-user/elfload.c > +++ b/linux-user/elfload.c > @@ -918,9 +918,9 @@ static inline void init_thread(struct target_pt_regs > *regs, > > #define elf_check_arch(x) ( (x) == ELF_ARCH ) > > -#define ELF_CLASS ELFCLASS64 > -#define ELF_DATA ELFDATA2MSB > -#define ELF_ARCH EM_S390 > +#define ELF_CLASS ELFCLASS64 > +#define ELF_DATA ELFDATA2MSB > +#define ELF_ARCH EM_S390 Please don't make unrelated whitespace changes. > > static inline void init_thread(struct target_pt_regs *regs, struct > image_info *infop) > { > @@ -1565,11 +1565,16 @@ static void load_elf_image(const char *image_name, > int image_fd, > vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr); > vaddr_ps = TARGET_ELF_PAGESTART(vaddr); > > - error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po, > - elf_prot, MAP_PRIVATE | MAP_FIXED, > - image_fd, eppnt->p_offset - vaddr_po); > - if (error == -1) { > - goto exit_perror; > + /* Don't attempt to map 0 bytes len sections. > + Kernel also has this check. > + */ This comment could be better: /* mmap() will fail EINVAL if given a zero size, but a * segment with zero filesize is perfectly valid (and * handled by the kernel's ELF loading code). */ > + if (eppnt->p_filesz + vaddr_po != 0) { > + error = target_mmap(vaddr_ps, eppnt->p_filesz + > vaddr_po, > + elf_prot, MAP_PRIVATE | MAP_FIXED, > + image_fd, eppnt->p_offset - > vaddr_po); Something in your patch submission path is wrapping long lines. > + if (error == -1) { > + goto exit_perror; > + } QEMU coding style is four-space indents, but the indent in your new code is mostly eight-space. > } > > vaddr_ef = vaddr + eppnt->p_filesz; > Otherwise looks OK. -- PMM
Hi guys,
Please don't submit these patches yet - I will re-submit from a different
email, to lessen the
legal complications.
I'm also adding a couple of new patches - just a heads up, when
transferring structs or arrays
in a syscall/ioctl, pointers also need conversions between target memory
space and host memory space.
i.e.
#if HOST_LONG_BITS == 32 && TARGET_ABI_BITS == 32
case TYPE_LONG:
case TYPE_ULONG:
*(uint32_t *)dst = tswap32(*(uint32_t *)src);
break;
case TYPE_PTRVOID:
/* we actually convert pointer values between host and target */
if (to_host) {
*(uint32_t *)dst = (uint32_t)g2h(*(uint32_t*)src);
}
else {
*(uint32_t *)dst = (uint32_t)h2g(*(uint32_t*)src);
}
break;
Cheers,
Alex
On Tue, Feb 21, 2012 at 3:08 AM, Peter Maydell <peter.maydell@linaro.org>wrote:
> On 21 February 2012 10:42, Damian, Alexandru <alexandru.damian@intel.com>
> wrote:
> > Hi,
> >
> > I got a problem with QEMU refusing to load an ELF binary with 0-length
> > sections,
> > while the kernel has no issue doing this.
> >
> > This patch adds a check that has been in kernel since 2008 at least.
>
> CC'ing Riku (linux-user maintainer).
>
> >
> > Cheers,
> > Alex
> >
> > ----------------
> > commit a42e5231c1be5f09caeb6c73e34933cd7efa7023
> > Author: Alexandru DAMIAN <alexandru.damian@intel.com>
> > Date: Tue Feb 21 12:34:36 2012 +0200
> >
> > Do not attempt to map 0-length sections
> >
> > Mmap will return an invalid argument, but 0-length sections
> > are valid in any case. The kernel as a similar check
> > when loading elf binaries courtesy of jkosina@suse.cz.
> >
> > Signed-off-by: Alexandru Damian <alexandru.damian@intel.com>
>
> Convention is to submit patches as git-format-patch style emails.
>
> > diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> > index ea61d0d..71d0ae3 100644
> > --- a/linux-user/elfload.c
> > +++ b/linux-user/elfload.c
> > @@ -918,9 +918,9 @@ static inline void init_thread(struct target_pt_regs
> > *regs,
> >
> > #define elf_check_arch(x) ( (x) == ELF_ARCH )
> >
> > -#define ELF_CLASS ELFCLASS64
> > -#define ELF_DATA ELFDATA2MSB
> > -#define ELF_ARCH EM_S390
> > +#define ELF_CLASS ELFCLASS64
> > +#define ELF_DATA ELFDATA2MSB
> > +#define ELF_ARCH EM_S390
>
> Please don't make unrelated whitespace changes.
>
> >
> > static inline void init_thread(struct target_pt_regs *regs, struct
> > image_info *infop)
> > {
> > @@ -1565,11 +1565,16 @@ static void load_elf_image(const char
> *image_name,
> > int image_fd,
> > vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr);
> > vaddr_ps = TARGET_ELF_PAGESTART(vaddr);
> >
> > - error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po,
> > - elf_prot, MAP_PRIVATE | MAP_FIXED,
> > - image_fd, eppnt->p_offset - vaddr_po);
> > - if (error == -1) {
> > - goto exit_perror;
> > + /* Don't attempt to map 0 bytes len sections.
> > + Kernel also has this check.
> > + */
>
> This comment could be better:
> /* mmap() will fail EINVAL if given a zero size, but a
> * segment with zero filesize is perfectly valid (and
> * handled by the kernel's ELF loading code).
> */
>
> > + if (eppnt->p_filesz + vaddr_po != 0) {
> > + error = target_mmap(vaddr_ps, eppnt->p_filesz +
> > vaddr_po,
> > + elf_prot, MAP_PRIVATE |
> MAP_FIXED,
> > + image_fd, eppnt->p_offset -
> > vaddr_po);
>
> Something in your patch submission path is wrapping long lines.
>
> > + if (error == -1) {
> > + goto exit_perror;
> > + }
>
> QEMU coding style is four-space indents, but the indent in your new
> code is mostly eight-space.
>
> > }
> >
> > vaddr_ef = vaddr + eppnt->p_filesz;
> >
>
> Otherwise looks OK.
>
> -- PMM
>
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index ea61d0d..71d0ae3 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -918,9 +918,9 @@ static inline void init_thread(struct target_pt_regs *regs, #define elf_check_arch(x) ( (x) == ELF_ARCH ) -#define ELF_CLASS ELFCLASS64 -#define ELF_DATA ELFDATA2MSB -#define ELF_ARCH EM_S390 +#define ELF_CLASS ELFCLASS64 +#define ELF_DATA ELFDATA2MSB +#define ELF_ARCH EM_S390 static inline void init_thread(struct target_pt_regs *regs, struct
Hi, I got a problem with QEMU refusing to load an ELF binary with 0-length sections, while the kernel has no issue doing this. This patch adds a check that has been in kernel since 2008 at least. Cheers, Alex ---------------- commit a42e5231c1be5f09caeb6c73e34933cd7efa7023 Author: Alexandru DAMIAN <alexandru.damian@intel.com> Date: Tue Feb 21 12:34:36 2012 +0200 Do not attempt to map 0-length sections Mmap will return an invalid argument, but 0-length sections are valid in any case. The kernel as a similar check when loading elf binaries courtesy of jkosina@suse.cz. Signed-off-by: Alexandru Damian <alexandru.damian@intel.com> image_info *infop) { @@ -1565,11 +1565,16 @@ static void load_elf_image(const char *image_name, int image_fd, vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr); vaddr_ps = TARGET_ELF_PAGESTART(vaddr); - error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po, - elf_prot, MAP_PRIVATE | MAP_FIXED, - image_fd, eppnt->p_offset - vaddr_po); - if (error == -1) { - goto exit_perror; + /* Don't attempt to map 0 bytes len sections. + Kernel also has this check. + */ + if (eppnt->p_filesz + vaddr_po != 0) { + error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po, + elf_prot, MAP_PRIVATE | MAP_FIXED, + image_fd, eppnt->p_offset - vaddr_po); + if (error == -1) { + goto exit_perror; + } } vaddr_ef = vaddr + eppnt->p_filesz;