[glibc] elf: Check invalid hole in PT_LOAD segments [BZ #28838]

[glibc] elf: Check invalid hole in PT_LOAD segments [BZ #28838]

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2c0915cbf570cb9c8a65f1d20a55c5a7238e5b63

commit 2c0915cbf570cb9c8a65f1d20a55c5a7238e5b63
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Feb 15 06:57:11 2022 -0800

    elf: Check invalid hole in PT_LOAD segments [BZ #28838]
    
    Changes in v2:
    
    1. Update commit log.
    
    commit 163f625cf9becbb82dfec63a29e566324129c0cd
    Author: H.J. Lu <hjl.tools@gmail.com>
    Date:   Tue Dec 21 12:35:47 2021 -0800
    
        elf: Remove excessive p_align check on PT_LOAD segments [BZ #28688]
    
    removed the p_align check against the page size.  It caused the loader
    error or crash on elf/tst-p_align3 when loading elf/tst-p_alignmod3.so,
    which has the invalid p_align in PT_LOAD segments, added by
    
    commit d8d94863ef125a392b929732b37e07dc927fbcd1
    Author: H.J. Lu <hjl.tools@gmail.com>
    Date:   Tue Dec 21 13:42:28 2021 -0800
    
    The loader failure caused by a negative length passed to __mprotect is
    random, depending on architecture and toolchain.  Update _dl_map_segments
    to detect invalid holes.  This fixes BZ #28838.
    
    Reviewed-by: Florian Weimer <fweimer@redhat.com>

Diff:
---
 elf/dl-map-segments.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h
index b3513e7909..024175b2d5 100644
--- a/elf/dl-map-segments.h
+++ b/elf/dl-map-segments.h
@@ -112,6 +112,9 @@ _dl_map_segments (struct link_map *l, int fd,
              unallocated.  Then jump into the normal segment-mapping loop to
              handle the portion of the segment past the end of the file
              mapping.  */
+	  if (__glibc_unlikely (loadcmds[nloadcmds - 1].mapstart <
+				c->mapend))
+	    return N_("ELF load command address/offset not page-aligned");
           if (__glibc_unlikely
               (__mprotect ((caddr_t) (l->l_addr + c->mapend),
                            loadcmds[nloadcmds - 1].mapstart - c->mapend,