mirror of https://github.com/xemu-project/xemu.git
linux-user: Adjust initial brk when interpreter is close to executable
While we attempt to load a ET_DYN executable far away from TASK_UNMAPPED_BASE, we are not completely in control of the address space layout. If the interpreter lands close to the executable, leaving insufficient heap space, move brk. Tested-by: Helge Deller <deller@gmx.de> Signed-off-by: Helge Deller <deller@gmx.de> [rth: Re-order after ELF_ET_DYN_BASE patch so that we do not "temporarily break" tsan, and also to minimize the changes required. Remove image_info.reserve_brk as unused.] Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@ -3110,27 +3110,6 @@ static void load_elf_image(const char *image_name, int image_fd,
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load_addr = loaddr;
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load_addr = loaddr;
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if (pinterp_name != NULL) {
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if (pinterp_name != NULL) {
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/*
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* This is the main executable.
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*
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* Reserve extra space for brk.
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* We hold on to this space while placing the interpreter
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* and the stack, lest they be placed immediately after
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* the data segment and block allocation from the brk.
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*
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* 16MB is chosen as "large enough" without being so large as
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* to allow the result to not fit with a 32-bit guest on a
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* 32-bit host. However some 64 bit guests (e.g. s390x)
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* attempt to place their heap further ahead and currently
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* nothing stops them smashing into QEMUs address space.
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*/
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#if TARGET_LONG_BITS == 64
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info->reserve_brk = 32 * MiB;
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#else
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info->reserve_brk = 16 * MiB;
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#endif
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hiaddr += info->reserve_brk;
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if (ehdr->e_type == ET_EXEC) {
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if (ehdr->e_type == ET_EXEC) {
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/*
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/*
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* Make sure that the low address does not conflict with
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* Make sure that the low address does not conflict with
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@ -3221,7 +3200,8 @@ static void load_elf_image(const char *image_name, int image_fd,
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info->end_code = 0;
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info->end_code = 0;
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info->start_data = -1;
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info->start_data = -1;
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info->end_data = 0;
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info->end_data = 0;
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info->brk = 0;
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/* Usual start for brk is after all sections of the main executable. */
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info->brk = TARGET_PAGE_ALIGN(hiaddr);
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info->elf_flags = ehdr->e_flags;
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info->elf_flags = ehdr->e_flags;
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prot_exec = PROT_EXEC;
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prot_exec = PROT_EXEC;
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@ -3315,9 +3295,6 @@ static void load_elf_image(const char *image_name, int image_fd,
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info->end_data = vaddr_ef;
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info->end_data = vaddr_ef;
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}
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}
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}
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}
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if (vaddr_em > info->brk) {
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info->brk = vaddr_em;
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}
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#ifdef TARGET_MIPS
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#ifdef TARGET_MIPS
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} else if (eppnt->p_type == PT_MIPS_ABIFLAGS) {
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} else if (eppnt->p_type == PT_MIPS_ABIFLAGS) {
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Mips_elf_abiflags_v0 abiflags;
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Mips_elf_abiflags_v0 abiflags;
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@ -3646,6 +3623,19 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
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if (elf_interpreter) {
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if (elf_interpreter) {
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load_elf_interp(elf_interpreter, &interp_info, bprm->buf);
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load_elf_interp(elf_interpreter, &interp_info, bprm->buf);
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/*
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* While unusual because of ELF_ET_DYN_BASE, if we are unlucky
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* with the mappings the interpreter can be loaded above but
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* near the main executable, which can leave very little room
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* for the heap.
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* If the current brk has less than 16MB, use the end of the
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* interpreter.
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*/
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if (interp_info.brk > info->brk &&
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interp_info.load_bias - info->brk < 16 * MiB) {
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info->brk = interp_info.brk;
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}
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/* If the program interpreter is one of these two, then assume
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/* If the program interpreter is one of these two, then assume
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an iBCS2 image. Otherwise assume a native linux image. */
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an iBCS2 image. Otherwise assume a native linux image. */
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@ -3699,17 +3689,6 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
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bprm->core_dump = &elf_core_dump;
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bprm->core_dump = &elf_core_dump;
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#endif
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#endif
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/*
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* If we reserved extra space for brk, release it now.
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* The implementation of do_brk in syscalls.c expects to be able
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* to mmap pages in this space.
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*/
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if (info->reserve_brk) {
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abi_ulong start_brk = TARGET_PAGE_ALIGN(info->brk);
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abi_ulong end_brk = TARGET_PAGE_ALIGN(info->brk + info->reserve_brk);
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target_munmap(start_brk, end_brk - start_brk);
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}
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return 0;
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return 0;
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}
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}
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@ -30,7 +30,6 @@ struct image_info {
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abi_ulong start_data;
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abi_ulong start_data;
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abi_ulong end_data;
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abi_ulong end_data;
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abi_ulong brk;
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abi_ulong brk;
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abi_ulong reserve_brk;
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abi_ulong start_mmap;
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abi_ulong start_mmap;
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abi_ulong start_stack;
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abi_ulong start_stack;
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abi_ulong stack_limit;
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abi_ulong stack_limit;
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