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[llvm-readobj] - Fix a crash when DT_STRTAB is broken. 

We might have a crash scenario when we have an invalid DT_STRTAB value
that is larger than the file size. I've added a test case to demonstrate.

Differential revision: https://reviews.llvm.org/D76706
This commit is contained in:
Georgii Rymar 2020-03-24 17:26:52 +03:00
parent c16c07d4b9
commit 30c1f9a558
2 changed files with 33 additions and 6 deletions
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13
llvm/lib/Object/ELF.cpp
View File

@ -580,7 +580,18 @@ Expected<const uint8_t *> ELFFile<ELFT>::toMappedAddr(uint64_t VAddr) const {
if (Delta >= Phdr.p_filesz)
return createError("virtual address is not in any segment: 0x" +
Twine::utohexstr(VAddr));
return base() + Phdr.p_offset + Delta;
uint64_t Offset = Phdr.p_offset + Delta;
if (Offset >= getBufSize())
return createError("can't map virtual address 0x" +
Twine::utohexstr(VAddr) + " to the segment with index " +
Twine(&Phdr - (*ProgramHeadersOrError).data() + 1) +
": the segment ends at 0x" +
Twine::utohexstr(Phdr.p_offset + Phdr.p_filesz) +
", which is greater than the file size (0x" +
Twine::utohexstr(getBufSize()) + ")");
return base() + Offset;
}
template class llvm::object::ELFFile<ELF32LE>;

26
llvm/test/tools/llvm-readobj/ELF/loadname.test
View File

@ -1,6 +1,8 @@
## Check we are able to dump library soname properly.
# RUN: yaml2obj %s -o %t.o
## Test a valid object case first. We set 'FileSize' to 0x48, because this is a no-op,
## i.e. this value would be set if we had no 'FileSize' at all.
# RUN: yaml2obj -DDTSTRTABVAL=0x0 -DPHDRFILESIZE="0x48" %s -o %t.o
# RUN: llvm-readobj %t.o | FileCheck %s --check-prefix LLVM
# RUN: llvm-readelf --dynamic-table %t.o | FileCheck %s --check-prefix GNU
@ -33,7 +35,7 @@ Sections:
Link: .dynstr
Entries:
- Tag: DT_STRTAB
Value: 0x0000000000000000
Value: [[DTSTRTABVAL]]
- Tag: DT_STRSZ
Value: 0x0000000000000007
- Tag: DT_SONAME
@ -41,9 +43,23 @@ Sections:
- Tag: DT_NULL
Value: 0x0000000000000000
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R ]
VAddr: 0x0000
- Type: PT_LOAD
Flags: [ PF_R ]
VAddr: 0x0000
FileSize: [[PHDRFILESIZE]]
Sections:
- Section: .dynstr
- Section: .dynamic
## Check we do not crash when an object contains a DT_STRTAB entry whose address
## is past the end of the object.
## Note that we have to set p_filesz for PT_LOAD larger than DT_STRTAB value
## to trigger this particular warning.
# RUN: yaml2obj -DDTSTRTABVAL=0xFFFE -DPHDRFILESIZE=0xFFFF %s -o %t.err.1.o
# RUN: llvm-readobj %t.err.1.o 2>&1 | FileCheck %s -DFILE=%t.err.1.o --check-prefixes=BROKEN-OFFSET,BROKEN-OFFSET-LLVM
# RUN: llvm-readelf --dynamic-table %t.err.1.o 2>&1 | FileCheck %s -DFILE=%t.err.1.o --check-prefixes=BROKEN-OFFSET,BROKEN-OFFSET-GNU
# BROKEN-OFFSET: warning: '[[FILE]]': Unable to parse DT_STRTAB: can't map virtual address 0xfffe to the segment with index 1: the segment ends at 0x10077, which is greater than the file size (0x228)
# BROKEN-OFFSET-LLVM: LoadName: <String table is empty or was not found>
# BROKEN-OFFSET-GNU: 0x000000000000000e (SONAME) Library soname: [<String table is empty or was not found>]