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Code Issues Releases Wiki Activity

Explicit write() can subsume ftruncate()

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modified:   stub/src/amd64-linux.elf-so_main.c
	modified:   stub/src/i386-linux.elf-so_main.c
This commit is contained in:
John Reiser 2023-08-31 13:25:53 -07:00
parent d54315392e
commit cd3f69c290
2 changed files with 0 additions and 7 deletions
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4
src/stub/src/amd64-linux.elf-so_main.c
View File

@ -263,7 +263,6 @@ make_hatch_x86_64(
} }
else { // Does not fit at hi end of .text, so must use a new page "permanently" else { // Does not fit at hi end of .text, so must use a new page "permanently"
int mfd = memfd_create(addr_string("upx"), 0); // the directory entry int mfd = memfd_create(addr_string("upx"), 0); // the directory entry
ftruncate(mfd, 6);
Pwrite(mfd, addr_string("\x0f\x05\x5f\x5e\x5a\xc3"), 6); Pwrite(mfd, addr_string("\x0f\x05\x5f\x5e\x5a\xc3"), 6);
hatch = Pmap(0, 6, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0); hatch = Pmap(0, 6, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0);
close(mfd); close(mfd);
@ -306,7 +305,6 @@ make_hatch_ppc64(
} }
else { // Does not fit at hi end of .text, so must use a new page "permanently" else { // Does not fit at hi end of .text, so must use a new page "permanently"
int mfd = memfd_create(addr_string("upx"), 0); // the directory entry int mfd = memfd_create(addr_string("upx"), 0); // the directory entry
ftruncate(mfd,sizeof(code));
Pwrite(mfd, code, sizeof(code)); Pwrite(mfd, code, sizeof(code));
hatch = Pmap(0, sizeof(code), PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0); hatch = Pmap(0, sizeof(code), PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0);
close(mfd); close(mfd);
@ -345,7 +343,6 @@ make_hatch_arm64(
} }
else { // Does not fit at hi end of .text, so must use a new page "permanently" else { // Does not fit at hi end of .text, so must use a new page "permanently"
int mfd = memfd_create(addr_string("upx"), 0); // the directory entry int mfd = memfd_create(addr_string("upx"), 0); // the directory entry
ftruncate(mfd, sizeof(code));
Pwrite(mfd, code, sizeof(code)); Pwrite(mfd, code, sizeof(code));
void *mfd_addr = Pmap(0, sizeof(code), PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0); void *mfd_addr = Pmap(0, sizeof(code), PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0);
close(mfd); close(mfd);
@ -498,7 +495,6 @@ upx_so_main( // returns &escape_hatch
if (phdr->p_flags & PF_X) { if (phdr->p_flags & PF_X) {
int mfd = memfd_create(addr_string("upx"), 0); int mfd = memfd_create(addr_string("upx"), 0);
unsigned mfd_len = 0ul - PAGE_MASK; unsigned mfd_len = 0ul - PAGE_MASK;
ftruncate(mfd, mfd_len);
Pwrite(mfd, elf_tmp, binfo->sz_unc); // de-compressed Elf_Ehdr and Elf_Phdrs Pwrite(mfd, elf_tmp, binfo->sz_unc); // de-compressed Elf_Ehdr and Elf_Phdrs
Pwrite(mfd, binfo->sz_unc + va_load, mfd_len - binfo->sz_unc); // rest of 1st page Pwrite(mfd, binfo->sz_unc + va_load, mfd_len - binfo->sz_unc); // rest of 1st page

3
src/stub/src/i386-linux.elf-so_main.c
View File

@ -287,7 +287,6 @@ make_hatch_i386(
} }
else { // Does not fit at hi end of .text, so must use a new page "permanently" else { // Does not fit at hi end of .text, so must use a new page "permanently"
int mfd = memfd_create(addr_string("upx"), 0); // the directory entry int mfd = memfd_create(addr_string("upx"), 0); // the directory entry
//ftruncate(mfd, 4);
write(mfd, &escape, 4); write(mfd, &escape, 4);
hatch = mmap(0, 4, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0); hatch = mmap(0, 4, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0);
close(mfd); close(mfd);
@ -325,7 +324,6 @@ make_hatch_arm32(
} }
else { // Does not fit at hi end of .text, so must use a new page "permanently" else { // Does not fit at hi end of .text, so must use a new page "permanently"
int mfd = memfd_create(addr_string("upx"), 0); // the directory entry int mfd = memfd_create(addr_string("upx"), 0); // the directory entry
//ftruncate(mfd, 2*4);
write(mfd, &code, 2*4); write(mfd, &code, 2*4);
hatch = Pmap(0, 2*4, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0); hatch = Pmap(0, 2*4, PROT_READ|PROT_EXEC, MAP_SHARED, mfd, 0);
close(mfd); close(mfd);
@ -555,7 +553,6 @@ upx_so_main( // returns &escape_hatch
if (phdr->p_flags & PF_X) { if (phdr->p_flags & PF_X) {
int mfd = memfd_create(addr_string("upx"), 0); int mfd = memfd_create(addr_string("upx"), 0);
unsigned mfd_len = 0ul - page_mask; unsigned mfd_len = 0ul - page_mask;
ftruncate(mfd, mfd_len);
Pwrite(mfd, elf_tmp, binfo->sz_unc); // de-compressed Elf_Ehdr and Elf_Phdrs Pwrite(mfd, elf_tmp, binfo->sz_unc); // de-compressed Elf_Ehdr and Elf_Phdrs
Pwrite(mfd, binfo->sz_unc + va_load, mfd_len - binfo->sz_unc); // rest of 1st page Pwrite(mfd, binfo->sz_unc + va_load, mfd_len - binfo->sz_unc); // rest of 1st page