From: Jason Andryuk <jandryuk@gmail.com>
To: xen-devel@lists.xenproject.org
Cc: Jason Andryuk <jandryuk@gmail.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Ian Jackson <iwj@xenproject.org>, Jan Beulich <jbeulich@suse.com>,
Julien Grall <julien@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>
Subject: [PATCH] libelf: Handle PVH kernels lacking ENTRY elfnote
Date: Wed, 14 Oct 2020 11:31:50 -0400 [thread overview]
Message-ID: <20201014153150.83875-1-jandryuk@gmail.com> (raw)
Linux kernels only have an ENTRY elfnote when built with CONFIG_PV. A
kernel build CONFIG_PVH=y CONFIG_PV=n lacks the note. In this case,
virt_entry will be UNSET_ADDR, overwritten by the ELF header e_entry,
and fail the check against the virt address range.
Change the code to only check virt_entry against the virtual address
range if it was set upon entry to the function.
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
---
Maybe the overwriting of virt_entry could be removed, but I don't know
if there would be unintended consequences where (old?) kernels don't
have an elfnote, but do have an in-range e_entry? The failing kernel I
just looked at has an e_entry of 0x1000000.
Oh, it looks like Mini-OS doesn't set the entry ELFNOTE and relies on
e_entry (of 0) to pass these checks.
---
xen/common/libelf/libelf-dominfo.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/xen/common/libelf/libelf-dominfo.c b/xen/common/libelf/libelf-dominfo.c
index 508f08db42..1ecf35166b 100644
--- a/xen/common/libelf/libelf-dominfo.c
+++ b/xen/common/libelf/libelf-dominfo.c
@@ -416,6 +416,7 @@ static elf_errorstatus elf_xen_note_check(struct elf_binary *elf,
static elf_errorstatus elf_xen_addr_calc_check(struct elf_binary *elf,
struct elf_dom_parms *parms)
{
+ bool check_virt_entry = true;
uint64_t virt_offset;
if ( (parms->elf_paddr_offset != UNSET_ADDR) &&
@@ -456,8 +457,10 @@ static elf_errorstatus elf_xen_addr_calc_check(struct elf_binary *elf,
parms->virt_kstart = elf->pstart + virt_offset;
parms->virt_kend = elf->pend + virt_offset;
- if ( parms->virt_entry == UNSET_ADDR )
+ if ( parms->virt_entry == UNSET_ADDR ) {
parms->virt_entry = elf_uval(elf, elf->ehdr, e_entry);
+ check_virt_entry = false;
+ }
if ( parms->bsd_symtab )
{
@@ -476,11 +479,17 @@ static elf_errorstatus elf_xen_addr_calc_check(struct elf_binary *elf,
elf_msg(elf, " p2m_base = 0x%" PRIx64 "\n", parms->p2m_base);
if ( (parms->virt_kstart > parms->virt_kend) ||
- (parms->virt_entry < parms->virt_kstart) ||
- (parms->virt_entry > parms->virt_kend) ||
(parms->virt_base > parms->virt_kstart) )
{
- elf_err(elf, "ERROR: ELF start or entries are out of bounds\n");
+ elf_err(elf, "ERROR: ELF start is out of bounds\n");
+ return -1;
+ }
+
+ if ( check_virt_entry &&
+ ( (parms->virt_entry < parms->virt_kstart) ||
+ (parms->virt_entry > parms->virt_kend) ) )
+ {
+ elf_err(elf, "ERROR: ELF entry is out of bounds\n");
return -1;
}
--
2.26.2
next reply other threads:[~2020-10-14 15:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 15:31 Jason Andryuk [this message]
2020-10-14 15:52 ` [PATCH] libelf: Handle PVH kernels lacking ENTRY elfnote Wei Liu
2020-10-14 16:02 ` Jan Beulich
2020-10-14 16:27 ` Jason Andryuk
2020-10-15 7:00 ` Jan Beulich
2020-10-15 14:50 ` Jason Andryuk
2020-10-15 15:14 ` Jan Beulich
2020-10-15 17:27 ` Andrew Cooper
2020-10-16 16:28 ` Jason Andryuk
2020-10-19 7:38 ` Jan Beulich
2020-10-19 15:26 ` Jason Andryuk
2020-10-19 15:36 ` Jan Beulich
2020-10-15 15:03 ` Roger Pau Monné
2020-10-14 16:12 ` Jürgen Groß
2020-10-14 16:27 ` Jason Andryuk
2020-10-15 4:17 ` Jürgen Groß
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