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| author | H.J. Lu <hjl.tools@gmail.com> | 2023-06-22 14:30:31 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2023-06-30 10:42:42 -0700 |
| commit | 6259ab39410cdefc80077afea48ca9cb057f6005 (patch) | |
| tree | f8f3550b1563e2312598dc5618f6d2ab4f48ee0a | |
| parent | 9401024e5e6be0e1c3870e185daae865cd4501f4 (diff) | |
| download | glibc-6259ab39410cdefc80077afea48ca9cb057f6005.zip glibc-6259ab39410cdefc80077afea48ca9cb057f6005.tar.gz glibc-6259ab39410cdefc80077afea48ca9cb057f6005.tar.bz2 | |
ld.so: Always use MAP_COPY to map the first segment [BZ #30452]
The first segment in a shared library may be read-only, not executable.
To support LD_PREFER_MAP_32BIT_EXEC on such shared libraries, we also
check MAP_DENYWRITE to decide if MAP_32BIT should be passed to mmap.
Normally the first segment is mapped with MAP_COPY, which is defined
as (MAP_PRIVATE | MAP_DENYWRITE). But if the segment alignment is
greater than the page size, MAP_COPY isn't used to allocate enough
space to ensure that the segment can be properly aligned. Map the
first segment with MAP_COPY in this case to fix BZ #30452.
| -rw-r--r-- | elf/dl-map-segments.h | 2 | ||||
| -rw-r--r-- | sysdeps/x86_64/64/Makefile | 7 | ||||
| -rw-r--r-- | sysdeps/x86_64/64/tst-map-32bit-2.c | 1 | ||||
| -rw-r--r-- | sysdeps/x86_64/64/tst-map-32bit-mod-2.c | 1 |
4 files changed, 10 insertions, 1 deletions
diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index 504cfc0..ac10182 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -36,7 +36,7 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, : (2 * c->mapalign)); ElfW(Addr) map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplen, PROT_NONE, - MAP_ANONYMOUS|MAP_PRIVATE, + MAP_ANONYMOUS|MAP_COPY, -1, 0); if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) return map_start; diff --git a/sysdeps/x86_64/64/Makefile b/sysdeps/x86_64/64/Makefile index 73fcfe0..17f0081 100644 --- a/sysdeps/x86_64/64/Makefile +++ b/sysdeps/x86_64/64/Makefile @@ -3,13 +3,16 @@ ifeq ($(subdir),elf) tests-map-32bit = \ tst-map-32bit-1a \ tst-map-32bit-1b \ + tst-map-32bit-2 \ # tests-map-32bit tst-map-32bit-1a-no-pie = yes tst-map-32bit-1b-no-pie = yes +tst-map-32bit-2-no-pie = yes tests += $(tests-map-32bit) modules-map-32bit = \ tst-map-32bit-mod \ + tst-map-32bit-mod-2 \ # modules-map-32bit modules-names += $(modules-map-32bit) @@ -18,5 +21,9 @@ tst-map-32bit-1a-ENV = LD_PREFER_MAP_32BIT_EXEC=1 $(objpfx)tst-map-32bit-1a: $(objpfx)tst-map-32bit-mod.so tst-map-32bit-1b-ENV = GLIBC_TUNABLES=glibc.cpu.prefer_map_32bit_exec=1 $(objpfx)tst-map-32bit-1b: $(objpfx)tst-map-32bit-mod.so +LDFLAGS-tst-map-32bit-mod-2.so += -Wl,-z,max-page-size=0x200000 +$(objpfx)tst-map-32bit-mod-2.so: $(libsupport) +tst-map-32bit-2-ENV = LD_PREFER_MAP_32BIT_EXEC=1 +$(objpfx)tst-map-32bit-2: $(objpfx)tst-map-32bit-mod-2.so endif diff --git a/sysdeps/x86_64/64/tst-map-32bit-2.c b/sysdeps/x86_64/64/tst-map-32bit-2.c new file mode 100644 index 0000000..34ab01c --- /dev/null +++ b/sysdeps/x86_64/64/tst-map-32bit-2.c @@ -0,0 +1 @@ +#include "tst-map-32bit-1a.c" diff --git a/sysdeps/x86_64/64/tst-map-32bit-mod-2.c b/sysdeps/x86_64/64/tst-map-32bit-mod-2.c new file mode 100644 index 0000000..69e795c --- /dev/null +++ b/sysdeps/x86_64/64/tst-map-32bit-mod-2.c @@ -0,0 +1 @@ +#include "tst-map-32bit-mod.c" |