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| author | Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com> | 2018-08-29 04:23:27 -0500 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2018-09-25 22:36:49 +0200 |
| commit | 94894ff2d13c85a840f80387c573a34ed6c99063 (patch) | |
| tree | 2d213369624e4e23fa8010c9bd7136b947bd8480 /linux-user/elfload.c | |
| parent | 83eb6e509062b8907eb95a00170ef6dde8d264fd (diff) | |
| download | qemu-94894ff2d13c85a840f80387c573a34ed6c99063.zip qemu-94894ff2d13c85a840f80387c573a34ed6c99063.tar.gz qemu-94894ff2d13c85a840f80387c573a34ed6c99063.tar.bz2 | |
linux-user: elf: mmap all the target-pages of hostpage for data segment
If the hostpage size is greater than the TARGET_PAGESIZE, the
target-pages of size TARGET_PAGESIZE are marked valid only till the
length requested during the elfload. The glibc attempts to consume unused
space in the last page of data segment(__libc_memalign() in
elf/dl-minimal.c). If PT_LOAD p_align is greater than or
equal to hostpage size, the GLRO(dl_pagesize) is actually the host pagesize
as set in the auxillary vectors. So, there is no explicit mmap request for
the remaining target-pages on the last hostpage. The glibc assumes that
particular space as available and subsequent attempts to use
those addresses lead to crash as the target_mmap has not marked them valid
for those target-pages.
The issue is seen when trying to chroot to 16.04-x86_64 ubuntu on a PPC64
host where the fork fails to access the thread_id as it is allocated on a
page not marked valid. The recent glibc doesn't have checks for thread-id in
fork, but the issue can manifest somewhere else, none the less.
The fix here is to map all the target-pages of the hostpage during the
elfload if the p_align is greater than or equal to hostpage size, for
data segment to allow the glibc for proper consumption.
Signed-off-by: Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <153553435604.51992.5640085189104207249.stgit@lep8c.aus.stglabs.ibm.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Diffstat (limited to 'linux-user/elfload.c')
| -rw-r--r-- | linux-user/elfload.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 8638612..6ead0d1 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1437,7 +1437,10 @@ struct exec #define QMAGIC 0314 /* Necessary parameters */ -#define TARGET_ELF_EXEC_PAGESIZE TARGET_PAGE_SIZE +#define TARGET_ELF_EXEC_PAGESIZE \ + (((eppnt->p_align & ~qemu_host_page_mask) != 0) ? \ + TARGET_PAGE_SIZE : MAX(qemu_host_page_size, TARGET_PAGE_SIZE)) +#define TARGET_ELF_PAGELENGTH(_v) ROUND_UP((_v), TARGET_ELF_EXEC_PAGESIZE) #define TARGET_ELF_PAGESTART(_v) ((_v) & \ ~(abi_ulong)(TARGET_ELF_EXEC_PAGESIZE-1)) #define TARGET_ELF_PAGEOFFSET(_v) ((_v) & (TARGET_ELF_EXEC_PAGESIZE-1)) @@ -2279,7 +2282,7 @@ static void load_elf_image(const char *image_name, int image_fd, for (i = 0; i < ehdr->e_phnum; i++) { struct elf_phdr *eppnt = phdr + i; if (eppnt->p_type == PT_LOAD) { - abi_ulong vaddr, vaddr_po, vaddr_ps, vaddr_ef, vaddr_em; + abi_ulong vaddr, vaddr_po, vaddr_ps, vaddr_ef, vaddr_em, vaddr_len; int elf_prot = 0; if (eppnt->p_flags & PF_R) elf_prot = PROT_READ; @@ -2289,8 +2292,9 @@ static void load_elf_image(const char *image_name, int image_fd, vaddr = load_bias + eppnt->p_vaddr; vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr); vaddr_ps = TARGET_ELF_PAGESTART(vaddr); + vaddr_len = TARGET_ELF_PAGELENGTH(eppnt->p_filesz + vaddr_po); - error = target_mmap(vaddr_ps, eppnt->p_filesz + vaddr_po, + error = target_mmap(vaddr_ps, vaddr_len, elf_prot, MAP_PRIVATE | MAP_FIXED, image_fd, eppnt->p_offset - vaddr_po); if (error == -1) { |