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Cleanup "PT_LOAD gap recovery" during upx -d

Browse Source 
https://github.com/upx/upx/issues/635
	modified:   p_lx_elf.cpp
This commit is contained in:
John Reiser
2022-12-21 06:53:37 -08:00
committed by Markus F.X.J. Oberhumer
parent 0ac3cb2329
commit fefce0d5c4
1 changed files with 32 additions and 26 deletions
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src/p_lx_elf.cpp
+32 -26
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@@ -5405,34 +5405,40 @@ void PackLinuxElf64::unpack(OutputFile *fo)
get_te64(&phdr[j].p_filesz); get_te64(&phdr[j].p_filesz);
if (fo) if (fo)
fo->seek(where, SEEK_SET); fo->seek(where, SEEK_SET);
{ // Recover from some piracy [also serves as error tolerance :-) ] { // Recover from some piracy [also serves as error tolerance :-) ]
b_info b_peek; b_info b_peek;
fi->readx(&b_peek, sizeof(b_peek)); fi->readx(&b_peek, sizeof(b_peek));
upx_off_t pos = fi->seek(-(off_t)sizeof(b_peek), SEEK_CUR); upx_off_t pos = fi->seek(-(off_t)sizeof(b_peek), SEEK_CUR);
if (b_peek.sz_unc != size if (get_te32(&b_peek.sz_unc) != size
|| b_peek.b_method != prev_method) { || b_peek.b_method != prev_method) {
opt->info_mode++; opt->info_mode++;
infoWarning("bad b_info at %#zx", (size_t)pos); infoWarning("bad b_info at %#zx", (size_t)pos);
unsigned const N_PEEK(64), H_PEEK(N_PEEK >> 1); unsigned const N_PEEK(64), H_PEEK(N_PEEK >> 1);
unsigned char peek_arr[N_PEEK]; unsigned char peek_arr[N_PEEK];
fi->seek(pos - H_PEEK, SEEK_SET); fi->seek(pos - H_PEEK, SEEK_SET);
fi->readx(peek_arr, sizeof(peek_arr)); fi->readx(peek_arr, sizeof(peek_arr));
fi->seek(pos + H_PEEK - sizeof(peek_arr), SEEK_SET);
int boff = find_le32(peek_arr, sizeof(peek_arr), size);
unsigned word1 = get_te32(&peek_arr[0*sizeof(int) + boff]);
unsigned word2 = get_te32(&peek_arr[1*sizeof(int) + boff]);
unsigned word3 = get_te32(&peek_arr[2*sizeof(int) + boff]);
if (0 <= boff // found
&& (((0 == word3) && (word1 == word2)) // uncompressible literal
|| prev_method == word3) // same method, no filter
) {
pos -= H_PEEK;
pos += boff;
infoWarning("... recovery at %#zx", (size_t)pos);
fi->seek(pos, SEEK_SET); fi->seek(pos, SEEK_SET);
int boff = find_le32(peek_arr, sizeof(peek_arr), size);
b_info *bp = (b_info *)(void *)&peek_arr[boff];
unsigned sz_unc = get_te32(&bp->sz_unc);
unsigned sz_cpr = get_te32(&bp->sz_cpr);
unsigned word3 = get_te32(&bp->b_method);
unsigned method = bp->b_method;
unsigned ftid = bp->b_ftid;
unsigned cto8 = bp->b_cto8;
if (0 <= boff // found
&& (((sz_unc == sz_cpr) && (0 == word3))// uncompressible literal
|| ((sz_cpr < sz_unc) && (method == prev_method)
&& (0 == ftid) && (0 == cto8)))
) {
pos -= H_PEEK;
pos += boff;
infoWarning("... recovery at %#zx", (size_t)pos);
fi->seek(pos, SEEK_SET);
}
opt->info_mode--;
} }
opt->info_mode--;
}
} }
unpackExtent(size, fo, unpackExtent(size, fo,
c_adler, u_adler, false, szb_info, c_adler, u_adler, false, szb_info,