From cdf38888ed30523b1a6ee199449a86dbd1d864ce Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Wed, 16 Aug 2017 18:56:14 -0400 Subject: binfmt_elf_fdpic: fix crash on MMU system with dynamic binaries In elf_fdpic_map_file() there is a test to ensure the dynamic section in user space is properly terminated. However it does so by dereferencing a user address directly. Add proper user space accessor. Signed-off-by: Nicolas Pitre Acked-by: Mickael GUENE Tested-by: Vincent Abriou Tested-by: Andras Szemzo --- fs/binfmt_elf_fdpic.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs/binfmt_elf_fdpic.c') diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 692e2a1fd2bb..6a56dea13876 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -835,6 +835,9 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, if (phdr->p_vaddr >= seg->p_vaddr && phdr->p_vaddr + phdr->p_memsz <= seg->p_vaddr + seg->p_memsz) { + Elf32_Dyn __user *dyn; + Elf32_Sword d_tag; + params->dynamic_addr = (phdr->p_vaddr - seg->p_vaddr) + seg->addr; @@ -847,8 +850,9 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, goto dynamic_error; tmp = phdr->p_memsz / sizeof(Elf32_Dyn); - if (((Elf32_Dyn *) - params->dynamic_addr)[tmp - 1].d_tag != 0) + dyn = (Elf32_Dyn __user *)params->dynamic_addr; + __get_user(d_tag, &dyn[tmp - 1].d_tag); + if (d_tag != 0) goto dynamic_error; break; } -- cgit v1.2.3-55-g7522