In grub-core/loader/i386/bsdXX.c and grub-core/loader/multiboot_elfxx.c, error
conditionals are simplified to statements such as "if (err)". Even though the
assumption that non-zero values give errors is correct, it would be clearer and
more consistent to compare these conditionals to GRUB_ERR_NONE.
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
In bsdXX.c and multiboot_elfxx.c, e_phnum is used to obtain the number of
program header table entries, but it wasn't being checked if the value was
there.
According to the elf(5) manual page,
"If the number of entries in the program header table is larger than or equal to
PN_XNUM (0xffff), this member holds PN_XNUM (0xffff) and the real number of
entries in the program header table is held in the sh_info member of the
initial entry in section header table. Otherwise, the sh_info member of the
initial entry contains the value zero."
Since this check wasn't being made, grub_elfXX_get_phnum() is being added to
elfXX.c to make this check and use e_phnum if it doesn't have PN_XNUM as a
value, else use sh_info. We also need to make sure e_phnum isn't greater than
PN_XNUM and sh_info isn't less than PN_XNUM.
Note that even though elf.c and elfXX.c are located in grub-core/kern, they are
compiled as modules and don't need the EXPORT_FUNC() macro to define the functions
in elf.h.
Also, changed casts of phnum to match variables being set as well as dropped
casts when unnecessary.
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
In bsdXX.c and multiboot_elfxx.c, e_shnum is used to obtain the number of
section header table entries, but it wasn't being checked if the value was
there.
According to the elf(5) manual page,
"If the number of entries in the section header table is larger than or equal to
SHN_LORESERVE (0xff00), e_shnum holds the value zero and the real number of
entries in the section header table is held in the sh_size member of the initial
entry in section header table. Otherwise, the sh_size member of the initial
entry in the section header table holds the value zero."
Since this check wasn't being made, grub_elfXX_get_shnum() is being added to
elfXX.c to make this check and use whichever member doesn't have a value of
zero. If both are zero, then we must return an error. We also need to make sure
that e_shnum doesn't have a value greater than or equal to SHN_LORESERVE and
sh_size isn't less than SHN_LORESERVE.
In order to get this function to work, the type ElfXX_Shnum is being added where
Elf32_Shnum defines Elf32_Word and Elf64_Shnum defines Elf64_Xword. This new
type is needed because if shnum obtains a value from sh_size, sh_size could be
of type El32_Word for Elf32_Shdr structures or Elf64_Xword for Elf64_Shdr
structures.
Note that even though elf.c and elfXX.c are located in grub-core/kern, they are
compiled as modules and don't need the EXPORT_FUNC() macro to define the functions
in elf.h.
For a few smaller changes, changed casts of shnum to match variables being set
as well as dropped casts when unnecessary and fixed spacing errors in bsdXX.c.
Also, shnum is an unsigned integer and is compared to int i in multiboot_elfxx.c,
it should be unsigned to match shnum.
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
In bsdXX.c, a couple of untrusted loop bound and untrusted allocation size bugs
were flagged by Coverity in the functions grub_openbsd_find_ramdisk() and
grub_freebsd_load_elfmodule(). These bugs were flagged by coverity because the
variable shdr was downcasting from a char pointer to an Elf_Shdr pointer
whenever it was used to set the base value in for loops. To avoid this, we need
to set shdr as an Elf_Shdr pointer where it is initialized.
In the function read_headers(), the function is reading elf section header data
from a file and passing it to the variable shdr as data for a char pointer. If
we switch the type of shdr to an Elf_Shdr pointer in read_headers() as well as
other functions, then we won't need to downcast to an Elf_Shdr pointer. By doing
this, the issue becomes masked from Coverity's view. In the following patches,
we check limits to ensure the data isn't tainted.
Also, switched use of (char *) to (grub_uint8_t *) to give a better indication
of pointer arithmetic and not suggest use of a C string.
Fixes: CID 314018
Fixes: CID 314030
Fixes: CID 314031
Fixes: CID 314039
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
This modifies most of the places we do some form of:
X = malloc(Y * Z);
to use calloc(Y, Z) instead.
Among other issues, this fixes:
- allocation of integer overflow in grub_png_decode_image_header()
reported by Chris Coulson,
- allocation of integer overflow in luks_recover_key()
reported by Chris Coulson,
- allocation of integer overflow in grub_lvm_detect()
reported by Chris Coulson.
Fixes: CVE-2020-14308
Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Alec Brown