| Message ID | 20240303-elf2dmp-v1-3-bea6649fe3e6@daynix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | contrib/elf2dmp: Improve robustness | expand |
On Sun, 3 Mar 2024 at 10:53, Akihiko Odaki <akihiko.odaki@daynix.com> wrote: > > This makes elf2dmp more robust against corrupted inputs. > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > --- > contrib/elf2dmp/addrspace.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/contrib/elf2dmp/addrspace.c b/contrib/elf2dmp/addrspace.c > index 980a7aa5f8fb..d546a400dfda 100644 > --- a/contrib/elf2dmp/addrspace.c > +++ b/contrib/elf2dmp/addrspace.c > @@ -88,11 +88,12 @@ int pa_space_create(struct pa_space *ps, QEMU_Elf *qemu_elf) > ps->block = g_new(struct pa_block, ps->block_nr); > > for (i = 0; i < phdr_nr; i++) { > - if (phdr[i].p_type == PT_LOAD) { > + if (phdr[i].p_type == PT_LOAD && phdr[i].p_offset < qemu_elf->size) { > ps->block[block_i] = (struct pa_block) { > .addr = (uint8_t *)qemu_elf->map + phdr[i].p_offset, > .paddr = phdr[i].p_paddr, > - .size = phdr[i].p_filesz, > + .size = MIN(phdr[i].p_filesz, > + qemu_elf->size - phdr[i].p_offset), Shouldn't "p_filesz is smaller than the actual amount of data in the file" be a failure condition? In include/hw/elf_ops.h we treat it that way: mem_size = ph->p_memsz; /* Size of the ROM */ file_size = ph->p_filesz; /* Size of the allocated data */ data_offset = ph->p_offset; /* Offset where the data is located */ if (file_size > 0) { if (g_mapped_file_get_length(mapped_file) < file_size + data_offset) { goto fail; } [etc] Like that code, we could then only check if p_offset + p_filesz is off the end of the file, rather than checking p_offset separately. > }; > pa_block_align(&ps->block[block_i]); > block_i = ps->block[block_i].size ? (block_i + 1) : block_i; thanks -- PMM
On 2024/03/05 2:52, Peter Maydell wrote: > On Sun, 3 Mar 2024 at 10:53, Akihiko Odaki <akihiko.odaki@daynix.com> wrote: >> >> This makes elf2dmp more robust against corrupted inputs. >> >> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> >> --- >> contrib/elf2dmp/addrspace.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/contrib/elf2dmp/addrspace.c b/contrib/elf2dmp/addrspace.c >> index 980a7aa5f8fb..d546a400dfda 100644 >> --- a/contrib/elf2dmp/addrspace.c >> +++ b/contrib/elf2dmp/addrspace.c >> @@ -88,11 +88,12 @@ int pa_space_create(struct pa_space *ps, QEMU_Elf *qemu_elf) >> ps->block = g_new(struct pa_block, ps->block_nr); >> >> for (i = 0; i < phdr_nr; i++) { >> - if (phdr[i].p_type == PT_LOAD) { >> + if (phdr[i].p_type == PT_LOAD && phdr[i].p_offset < qemu_elf->size) { >> ps->block[block_i] = (struct pa_block) { >> .addr = (uint8_t *)qemu_elf->map + phdr[i].p_offset, >> .paddr = phdr[i].p_paddr, >> - .size = phdr[i].p_filesz, >> + .size = MIN(phdr[i].p_filesz, >> + qemu_elf->size - phdr[i].p_offset), > > Shouldn't "p_filesz is smaller than the actual amount of data in the > file" be a failure condition? In include/hw/elf_ops.h we treat it > that way: > > mem_size = ph->p_memsz; /* Size of the ROM */ > file_size = ph->p_filesz; /* Size of the allocated data */ > data_offset = ph->p_offset; /* Offset where the data is located */ > > if (file_size > 0) { > if (g_mapped_file_get_length(mapped_file) < > file_size + data_offset) { > goto fail; > } > [etc] > > Like that code, we could then only check if p_offset + p_filesz is off > the end of the file, rather than checking p_offset separately. > >> }; >> pa_block_align(&ps->block[block_i]); >> block_i = ps->block[block_i].size ? (block_i + 1) : block_i; > > thanks > -- PMM I'm making this permissive for corrupted dumps since they may still include valuable information. It is different from include/hw/elf_ops.h, which is presumably used to load executables rather than dumps. Loading a corrupted executable does nothing good. Regards, Akihiko Odaki
diff --git a/contrib/elf2dmp/addrspace.c b/contrib/elf2dmp/addrspace.c index 980a7aa5f8fb..d546a400dfda 100644 --- a/contrib/elf2dmp/addrspace.c +++ b/contrib/elf2dmp/addrspace.c @@ -88,11 +88,12 @@ int pa_space_create(struct pa_space *ps, QEMU_Elf *qemu_elf) ps->block = g_new(struct pa_block, ps->block_nr); for (i = 0; i < phdr_nr; i++) { - if (phdr[i].p_type == PT_LOAD) { + if (phdr[i].p_type == PT_LOAD && phdr[i].p_offset < qemu_elf->size) { ps->block[block_i] = (struct pa_block) { .addr = (uint8_t *)qemu_elf->map + phdr[i].p_offset, .paddr = phdr[i].p_paddr, - .size = phdr[i].p_filesz, + .size = MIN(phdr[i].p_filesz, + qemu_elf->size - phdr[i].p_offset), }; pa_block_align(&ps->block[block_i]); block_i = ps->block[block_i].size ? (block_i + 1) : block_i;
This makes elf2dmp more robust against corrupted inputs. Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> --- contrib/elf2dmp/addrspace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)