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ELF: fix overflow in total mapping size calculation
Kernel assumes that ELF program headers are ordered by mapping address, but doesn't enforce it. It is possible to make mapping size extremely huge by simply shuffling first and last PT_LOAD segments. As long as PT_LOAD segments do not overlap, it is silly to require sorting by v_addr anyway because mmap() doesn't care. Don't assume PT_LOAD segments are sorted and calculate min and max addresses correctly. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Tested-by: "Magnus Groß" <magnus.gross@rwth-aachen.de> Link: https://lore.kernel.org/all/Yfqm7HbucDjPbES+@fractal.localdomain/ Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/lkml/YVmd7D0M6G%2FDcP4O@localhost.localdomain
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@ -93,7 +93,7 @@ static int elf_core_dump(struct coredump_params *cprm);
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#define ELF_CORE_EFLAGS 0
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#endif
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#define ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(ELF_MIN_ALIGN-1))
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#define ELF_PAGESTART(_v) ((_v) & ~(int)(ELF_MIN_ALIGN-1))
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#define ELF_PAGEOFFSET(_v) ((_v) & (ELF_MIN_ALIGN-1))
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#define ELF_PAGEALIGN(_v) (((_v) + ELF_MIN_ALIGN - 1) & ~(ELF_MIN_ALIGN - 1))
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@ -399,22 +399,21 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
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return(map_addr);
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}
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static unsigned long total_mapping_size(const struct elf_phdr *cmds, int nr)
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static unsigned long total_mapping_size(const struct elf_phdr *phdr, int nr)
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{
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int i, first_idx = -1, last_idx = -1;
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elf_addr_t min_addr = -1;
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elf_addr_t max_addr = 0;
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bool pt_load = false;
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int i;
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for (i = 0; i < nr; i++) {
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if (cmds[i].p_type == PT_LOAD) {
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last_idx = i;
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if (first_idx == -1)
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first_idx = i;
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if (phdr[i].p_type == PT_LOAD) {
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min_addr = min(min_addr, ELF_PAGESTART(phdr[i].p_vaddr));
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max_addr = max(max_addr, phdr[i].p_vaddr + phdr[i].p_memsz);
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pt_load = true;
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}
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}
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if (first_idx == -1)
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return 0;
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return cmds[last_idx].p_vaddr + cmds[last_idx].p_memsz -
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ELF_PAGESTART(cmds[first_idx].p_vaddr);
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return pt_load ? (max_addr - min_addr) : 0;
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}
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static int elf_read(struct file *file, void *buf, size_t len, loff_t pos)
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