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authorVincent Fazio <vfazio@gmail.com>2021-01-31 00:19:48 -0600
committerLaurent Vivier <laurent@vivier.eu>2021-03-13 10:45:11 +0100
commit0266e8e3b3981b492e82be20bb97e8ed9792ed00 (patch)
treedb718fb4ce62fe75ff6b2872dc4f6e430c6780ef
parent934eed517857ce2de9a8a92c2599612581b4eb4a (diff)
linux-user/elfload: fix address calculation in fallback scenario
Previously, guest_loaddr was not taken into account when returning an address from pgb_find_hole when /proc/self/maps was unavailable which caused an improper guest_base address to be calculated. This could cause a SIGSEGV later in load_elf_image -> target_mmap for ET_EXEC type images since the mmap MAP_FIXED flag is specified which could clobber existing mappings at the address returnd by g2h(). mmap(0xd87000, 16846912, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE|0x100000, -1, 0) = 0xd87000 munmap(0xd87000, 16846912) = 0 write(2, "Locating guest address space @ 0"..., 40Locating guest address space @ 0xd87000) = 40 mmap(0x1187000, 16850944, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x1187000 --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_ACCERR, si_addr=0x2188310} --- +++ killed by SIGSEGV +++ Now, pgd_find_hole accounts for guest_loaddr in this scenario. Fixes: ad592e37dfcc ("linux-user: provide fallback pgd_find_hole for bare chroots") Signed-off-by: Vincent Fazio <vfazio@gmail.com> Reviewed-by: Laurent Vivier <laurent@vivier.eu> Message-Id: <20210131061948.15990-1-vfazio@xes-inc.com> [lv: updated it to check if ret == -1] Signed-off-by: Laurent Vivier <laurent@vivier.eu>
-rw-r--r--linux-user/elfload.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index e525901659..c6731013fd 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2235,7 +2235,8 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size,
brk = (uintptr_t)sbrk(0);
if (!maps) {
- return pgd_find_hole_fallback(guest_size, brk, align, offset);
+ ret = pgd_find_hole_fallback(guest_size, brk, align, offset);
+ return ret == -1 ? -1 : ret - guest_loaddr;
}
/* The first hole is before the first map entry. */