diff options
| -rw-r--r-- | elf/rtld.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/elf/rtld.c b/elf/rtld.c index 4e0581e2c6..8d233f77be 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1147,6 +1147,22 @@ rtld_setup_main_map (struct link_map *main_map) main_map->l_map_start = ~0; /* And it was opened directly. */ ++main_map->l_direct_opencount; + main_map->l_contiguous = 1; + + /* A PT_LOAD segment at an unexpected address will clear the + l_contiguous flag. The ELF specification says that PT_LOAD + segments need to be sorted in in increasing order, but perhaps + not all executables follow this requirement. Having l_contiguous + equal to 1 is just an optimization, so the code below does not + try to sort the segments in case they are unordered. + + There is one corner case in which l_contiguous is not set to 1, + but where it could be set: If a PIE (ET_DYN) binary is loaded by + glibc itself (not the kernel), it is always contiguous due to the + way the glibc loader works. However, the kernel loader may still + create holes in this case, and the code here still uses 0 + conservatively for the glibc-loaded case, too. */ + ElfW(Addr) expected_load_address = 0; /* Scan the program header table for the dynamic section. */ for (const ElfW(Phdr) *ph = phdr; ph < &phdr[phnum]; ++ph) @@ -1210,12 +1226,21 @@ rtld_setup_main_map (struct link_map *main_map) if (main_map->l_map_start > mapstart) main_map->l_map_start = mapstart; + if (main_map->l_contiguous && expected_load_address != 0 + && expected_load_address != mapstart) + main_map->l_contiguous = 0; + /* Also where it ends. */ allocend = main_map->l_addr + ph->p_vaddr + ph->p_memsz; if (main_map->l_map_end < allocend) main_map->l_map_end = allocend; if ((ph->p_flags & PF_X) && allocend > main_map->l_text_end) main_map->l_text_end = allocend; + + /* The next expected address is the page following this load + segment. */ + expected_load_address = ((allocend + GLRO(dl_pagesize) - 1) + & ~(GLRO(dl_pagesize) - 1)); } break; |