From 480b6fa3662ba8ffeee274bf0d37423413c01e55 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Wed, 3 Mar 2021 21:40:53 +0100 Subject: [PATCH] readelf: Sanity check verneed and verdef offsets in handle_symtab. We are going through vna_next, vn_next and vd_next in a while loop. Make sure that all offsets are sane. We don't want things to wrap around so we go in cycles. https://sourceware.org/bugzilla/show_bug.cgi?id=27501 Signed-off-by: Mark Wielaard Upstream-Status: Backport [https://sourceware.org/git/?p=elfutils.git;a=commit;h=480b6fa3662ba8ffeee274bf0d37423413c01e55] CVE: CVE-2021-33294 Signed-off-by: Vijay Anusuri --- src/ChangeLog | 5 +++++ src/readelf.c | 10 +++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/src/ChangeLog b/src/ChangeLog index 6af977e..f0d9e39 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,8 @@ +2021-03-03 Mark Wielaard + + * readelf.c (handle_symtab): Sanity check verneed vna_next, + vn_next and verdef vd_next offsets. + 2019-11-26 Mark Wielaard * Makefile.am (BUILD_STATIC): Add libraries needed for libdw. diff --git a/src/readelf.c b/src/readelf.c index 5994615..ab7a1c1 100644 --- a/src/readelf.c +++ b/src/readelf.c @@ -2550,7 +2550,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr) &vernaux_mem); while (vernaux != NULL && vernaux->vna_other != *versym - && vernaux->vna_next != 0) + && vernaux->vna_next != 0 + && (verneed_data->d_size - vna_offset + >= vernaux->vna_next)) { /* Update the offset. */ vna_offset += vernaux->vna_next; @@ -2567,6 +2569,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr) /* Found it. */ break; + if (verneed_data->d_size - vn_offset < verneed->vn_next) + break; + vn_offset += verneed->vn_next; verneed = (verneed->vn_next == 0 ? NULL @@ -2602,6 +2607,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr) /* Found the definition. */ break; + if (verdef_data->d_size - vd_offset < verdef->vd_next) + break; + vd_offset += verdef->vd_next; verdef = (verdef->vd_next == 0 ? NULL -- 2.25.1