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[llvm-readobj] - Don't crash when checking the number of dynamic symbols. 

When we deriving the number of symbols from the DT_HASH table, we can crash when
calculate the number of symbols in the symbol table when SHT_DYNSYM
has sh_entsize == 0.

The patch fixes the issue.

Differential revision: https://reviews.llvm.org/D82877
This commit is contained in:
Georgii Rymar 2020-06-30 17:14:45 +03:00
parent 917bdfaca6
commit 61f967dcca
2 changed files with 27 additions and 9 deletions
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18
llvm/test/tools/llvm-readobj/ELF/dyn-symbols-size-from-hash-table.test
View File

@ -158,6 +158,20 @@ ProgramHeaders:
# RUN: FileCheck %s --check-prefixes=GNU2,GNU2-MORE,GNU2-ALL,WARN \
# RUN: --implicit-check-not=warning: -DNCHAIN=4
# WARN: warning: '{{.*}}2-{{.*}}': hash table nchain ([[NCHAIN]]) differs from symbol count derived from SHT_DYNSYM section header (3)
## Show we report a warning when the sh_entsize of the SHT_DYNSYM section is zero and therefore we are unable
## to derive the number of dynamic symbols from SHT_DYNSYM section header.
# RUN: yaml2obj --docnum=2 %s -o %t2-zero-entsize -DCHAIN="[1, 2, 3, 4]" -DENTSIZE=0
# RUN: llvm-readobj --dyn-symbols %t2-zero-entsize 2>&1 | \
# RUN: FileCheck %s -DFILE=%t2-zero-entsize --check-prefixes=LLVM2,LLVM2-MORE,LLVM2-ALL,WARN-ENTSIZE \
# RUN: --implicit-check-not=warning:
# RUN: llvm-readelf --dyn-symbols %t2-zero-entsize 2>&1 | \
# RUN: FileCheck %s -DFILE=%t2-zero-entsize --check-prefixes=GNU2,GNU2-MORE,GNU2-ALL,WARN-ENTSIZE \
# RUN: --implicit-check-not=warning: -DNCHAIN=4
## WARN-ENTSIZE: warning: '[[FILE]]': SHT_DYNSYM section has sh_entsize == 0
## Show there's no warning if the sizes match
# RUN: yaml2obj --docnum=2 %s -o %t2-same -DCHAIN="[1, 2, 3]"
# RUN: llvm-readobj --dyn-symbols %t2-same 2>&1 | \
@ -166,8 +180,6 @@ ProgramHeaders:
# RUN: FileCheck %s --check-prefixes=GNU2,GNU2-MORE \
# RUN: --implicit-check-not=warning: -DNCHAIN=3
# WARN: warning: '{{.*}}2-{{.*}}': hash table nchain ([[NCHAIN]]) differs from symbol count derived from SHT_DYNSYM section header (3)
# LLVM2: DynamicSymbols [
# LLVM2-NEXT: Symbol {
# LLVM2-NEXT: Name: (0)
@ -236,6 +248,8 @@ Sections:
ShSize: 0x48
Address: 0x400
AddressAlign: 0x400
## 0x18 is the standard entsize value.
EntSize: [[ENTSIZE=0x18]]
- Name: .hash
Type: SHT_HASH
Flags: [ SHF_ALLOC ]

8
llvm/tools/llvm-readobj/ELFDumper.cpp
View File

@ -2215,14 +2215,18 @@ void ELFDumper<ELFT>::parseDynamicTable(const ELFFile<ELFT> *Obj) {
// equal nchain". Check to see if the DT_HASH hash table nchain value
// conflicts with the number of symbols in the dynamic symbol table
// according to the section header.
if (HashTable &&
HashTable->nchain != DynSymRegion->Size / DynSymRegion->EntSize)
if (HashTable) {
if (DynSymRegion->EntSize == 0)
reportUniqueWarning(
createError("SHT_DYNSYM section has sh_entsize == 0"));
else if (HashTable->nchain != DynSymRegion->Size / DynSymRegion->EntSize)
reportUniqueWarning(createError(
"hash table nchain (" + Twine(HashTable->nchain) +
") differs from symbol count derived from SHT_DYNSYM section "
"header (" +
Twine(DynSymRegion->Size / DynSymRegion->EntSize) + ")"));
}
}
// Delay the creation of the actual dynamic symbol table until now, so that
// checks can always be made against the section header-based properties,