If the LOAD segment VMAs are extended to prevent creating additional
VMAs, the the protection extent of the GNU_RELRO segment must also
be updated to match. Otherwise, the partial mprotect will reintroduce
an additional VMA due to the split protections.
Update the GNU_RELRO protection range when the ELF was loaded by the
bionic loader. Be careful not to attempt any fix up for ELFs not loaded
by us (e.g. ELF loaded by the kernel) since these don't have the
extended VMA fix to begin with.
Consider a system with 4KB page size and the ELF files with 64K
alignment. e.g:
$ readelf -Wl /system/lib64/bootstrap/libc.so | grep 'Type\|LOAD'
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0441a8 0x0441a8 R 0x10000
LOAD 0x0441b0 0x00000000000541b0 0x00000000000541b0 0x091860 0x091860 R E 0x10000
LOAD 0x0d5a10 0x00000000000f5a10 0x00000000000f5a10 0x003d40 0x003d40 RW 0x10000
LOAD 0x0d9760 0x0000000000109760 0x0000000000109760 0x0005c0 0x459844 RW 0x10000
Before this patch:
$ cat /proc/1/maps | grep -A1 libc.so
7f468f069000-7f468f0bd000 r--p 00000000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f0bd000-7f468f15e000 r-xp 00044000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f15e000-7f468f163000 r--p 000d5000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f163000-7f468f172000 rw-p 000da000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f172000-7f468f173000 rw-p 000d9000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f173000-7f468f5c4000 rw-p 00000000 00:00 0 [anon:.bss]
1 extra RW VMA at offset 0x000da000 (3 RW mappings in total)
After this patch:
$ cat /proc/1/maps | grep -A1 libc.so
7f5a50225000-7f5a50279000 r--p 00000000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f5a50279000-7f5a5031a000 r-xp 00044000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f5a5031a000-7f5a5032e000 r--p 000d5000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f5a5032e000-7f5a5032f000 rw-p 000d9000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f5a5032f000-7f5a50780000 rw-p 00000000 00:00 0 [anon:.bss]
Removed RW VMA at offset 0x000da000 (2 RW mappings in total)
Bug: 316403210
Bug: 300367402
Bug: 307803052
Bug: 312550202
Test: atest -c linker-unit-tests [ Later patch ]
Test: atest -c bionic-unit-tests
Change-Id: If1d99e8b872fcf7f6e0feb02ff33503029b63be3
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
33f89709bc