From 09ec02ec7f7e6913d10943148e2a898264345b07 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Fri, 21 Oct 2016 15:24:34 +0200 Subject: [PATCH] libelf: Sanity check offset and size before trying to malloc and read data. Bad sh_off or sh_size could trigger a bad malloc or read. Sanity check the header values first before trying to malloc a huge buffer or reading any data that will certainly fail. https://bugzilla.redhat.com/show_bug.cgi?id=1387584 Signed-off-by: Mark Wielaard --- libelf/ChangeLog | 5 +++++ libelf/elf_getdata.c | 11 +++++++++++ 2 files changed, 16 insertions(+) diff --git a/libelf/ChangeLog b/libelf/ChangeLog index 39fbccf28..641412887 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2016-10-21 Mark Wielaard + + * elf_getdata.c (__libelf_set_rawdata_wrlock): Sanity check + offset and size before trying to malloc and read data. + 2016-10-26 Mark Wielaard * elf_begin.c (read_file): Always set maxsize when parent == NULL. diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c index d1fafbfe7..97c503b53 100644 --- a/libelf/elf_getdata.c +++ b/libelf/elf_getdata.c @@ -312,6 +312,17 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn) } else if (likely (elf->fildes != -1)) { + /* First see whether the information in the section header is + valid and it does not ask for too much. Check for unsigned + overflow. */ + if (unlikely (offset > elf->maximum_size + || elf->maximum_size - offset < size)) + { + /* Something is wrong. */ + __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER); + return 1; + } + /* We have to read the data from the file. Allocate the needed memory. */ scn->rawdata_base = scn->rawdata.d.d_buf -- 2.47.3