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rtld: do not try to mmap a zero-sized PT_LOAD

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When a PT_LOAD segment has a zero p_filesz, skip the data mmap, as mmapping
zero bytes from a file is an error.

A PT_LOAD with zero p_filesz is legal (but somewhat uncommon due to segment
merging in modern linkers, as it is more efficient to merge .data and .bss
by just extending p_memsz in the previous segment, assuming compatible
page protection.)

This was seen on ports/graphics/glew on a powerpc64 ELFv2 experimental
build.

Submitted by:	Alfredo Dal'Ava Junior <alfredo.junior@eldorado.org.br>
Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D22634
This commit is contained in:
Brandon Bergren 2019-12-12 17:40:32 +00:00
parent 4f9ed3156c
commit 44c9aa49ea
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=355657
1 changed files with 6 additions and 5 deletions
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11
libexec/rtld-elf/map_object.c
View File

@ -228,11 +228,12 @@ map_object(int fd, const char *path, const struct stat *sb)
data_addr = mapbase + (data_vaddr - base_vaddr);
data_prot = convert_prot(segs[i]->p_flags);
data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
if (mmap(data_addr, data_vlimit - data_vaddr, data_prot,
data_flags | MAP_PREFAULT_READ, fd, data_offset) == (caddr_t) -1) {
_rtld_error("%s: mmap of data failed: %s", path,
rtld_strerror(errno));
goto error1;
if (data_vlimit != data_vaddr &&
mmap(data_addr, data_vlimit - data_vaddr, data_prot,
data_flags | MAP_PREFAULT_READ, fd, data_offset) == MAP_FAILED) {
_rtld_error("%s: mmap of data failed: %s", path,
rtld_strerror(errno));
goto error1;
}
/* Do BSS setup */