commit 5035c0821f07da3badda645cd0064d4b80e1667d
 Author: Philipp Rudo <prudo@redhat.com>
 Date:   Mon Mar 14 17:04:32 2022 +0100
 
     [PATCH] print error when reading with unsupported compression
     
     Currently makedumpfile only checks if the required compression algorithm
     was enabled during build when compressing a dump but not when reading
     from one. This can lead to situations where, one version of makedumpfile
     creates the dump using a compression algorithm an other version of
     makedumpfile doesn't support. When the second version now tries to, e.g.
     extract the dmesg from the dump it will fail with an error similar to
     
       # makedumpfile --dump-dmesg vmcore dmesg.txt
       __vtop4_x86_64: Can't get a valid pgd.
       readmem: Can't convert a virtual address(ffffffff92e18284) to physical address.
       readmem: type_addr: 0, addr:ffffffff92e18284, size:390
       check_release: Can't get the address of system_utsname.
     
       makedumpfile Failed.
     
     That's because readpage_kdump_compressed{_parallel} does not return
     with an error if the page it is trying to read is compressed with an
     unsupported compression algorithm. Thus readmem copies random data from
     the (uninitialized) cachebuf to its caller and thus causing the error
     above.
     
     Fix this by checking if the required compression algorithm is supported
     in readpage_kdump_compressed{_parallel} and print a proper error message
     if it isn't.
     
     Reported-by: Dave Wysochanski <dwysocha@redhat.com>
     Signed-off-by: Philipp Rudo <prudo@redhat.com>
     Reviewed-and-tested-by: Dave Wysochanski <dwysocha@redhat.com>
     Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
 
 diff --git a/makedumpfile-1.7.0/makedumpfile.c b/makedumpfile-1.7.0/makedumpfile.c
 index 2b94446b8f2ad513da060e15821544ae32e1a2c6..14556db15627617cb394bba85bb7ebec6b35fb34 100644
 --- a/makedumpfile-1.7.0/makedumpfile.c
 +++ b/makedumpfile-1.7.0/makedumpfile.c
 @@ -865,9 +865,13 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +	} else if ((pd.flags & DUMP_DH_COMPRESSED_LZO)) {
  #ifdef USELZO
 -	} else if (info->flag_lzo_support
 -		   && (pd.flags & DUMP_DH_COMPRESSED_LZO)) {
 +		if (!info->flag_lzo_support) {
 +			ERRMSG("lzo compression unsupported\n");
 +			return FALSE;
 +		}
 +
  		retlen = info->page_size;
  		ret = lzo1x_decompress_safe((unsigned char *)buf, pd.size,
  					    (unsigned char *)bufptr, &retlen,
 @@ -876,9 +880,13 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("lzo compression unsupported\n");
 +		ERRMSG("Try `make USELZO=on` when building.\n");
 +		return FALSE;
  #endif
 -#ifdef USESNAPPY
  	} else if ((pd.flags & DUMP_DH_COMPRESSED_SNAPPY)) {
 +#ifdef USESNAPPY
  
  		ret = snappy_uncompressed_length(buf, pd.size, (size_t *)&retlen);
  		if (ret != SNAPPY_OK) {
 @@ -891,14 +899,22 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("snappy compression unsupported\n");
 +		ERRMSG("Try `make USESNAPPY=on` when building.\n");
 +		return FALSE;
  #endif
 -#ifdef USEZSTD
  	} else if ((pd.flags & DUMP_DH_COMPRESSED_ZSTD)) {
 +#ifdef USEZSTD
  		ret = ZSTD_decompress(bufptr, info->page_size, buf, pd.size);
  		if (ZSTD_isError(ret) || (ret != info->page_size)) {
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("zstd compression unsupported\n");
 +		ERRMSG("Try `make USEZSTD=on` when building.\n");
 +		return FALSE;
  #endif
  	}
  
 @@ -964,9 +980,13 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +	} else if ((pd.flags & DUMP_DH_COMPRESSED_LZO)) {
  #ifdef USELZO
 -	} else if (info->flag_lzo_support
 -		   && (pd.flags & DUMP_DH_COMPRESSED_LZO)) {
 +		if (!info->flag_lzo_support) {
 +			ERRMSG("lzo compression unsupported\n");
 +			return FALSE;
 +		}
 +
  		retlen = info->page_size;
  		ret = lzo1x_decompress_safe((unsigned char *)buf, pd.size,
  					    (unsigned char *)bufptr, &retlen,
 @@ -975,9 +995,13 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("lzo compression unsupported\n");
 +		ERRMSG("Try `make USELZO=on` when building.\n");
 +		return FALSE;
  #endif
 -#ifdef USESNAPPY
  	} else if ((pd.flags & DUMP_DH_COMPRESSED_SNAPPY)) {
 +#ifdef USESNAPPY
  
  		ret = snappy_uncompressed_length(buf, pd.size, (size_t *)&retlen);
  		if (ret != SNAPPY_OK) {
 @@ -990,14 +1014,22 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("snappy compression unsupported\n");
 +		ERRMSG("Try `make USESNAPPY=on` when building.\n");
 +		return FALSE;
  #endif
 -#ifdef USEZSTD
  	} else if ((pd.flags & DUMP_DH_COMPRESSED_ZSTD)) {
 +#ifdef USEZSTD
  		ret = ZSTD_decompress(bufptr, info->page_size, buf, pd.size);
  		if (ZSTD_isError(ret) || (ret != info->page_size)) {
  			ERRMSG("Uncompress failed: %d\n", ret);
  			return FALSE;
  		}
 +#else
 +		ERRMSG("zstd compression unsupported\n");
 +		ERRMSG("Try `make USEZSTD=on` when building.\n");
 +		return FALSE;
  #endif
  	}