-----Original Message-----
> 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@xxxxxxxxxx>
> Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxx>
> ---
> makedumpfile.c | 56 ++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 48 insertions(+), 8 deletions(-)
>
> diff --git a/makedumpfile.c b/makedumpfile.c
> index b7ac999..56f3b6c 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -865,9 +865,14 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> + } 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");
> + out = FALSE;
I removed those "out = FALSE;" lines because it's already initialized to FALSE.
Thanks,
Kazu
> + goto out_error;
> + }
> +
> retlen = info->page_size;
> ret = lzo1x_decompress_safe((unsigned char *)buf, pd.size,
> (unsigned char *)bufptr, &retlen,
> @@ -876,9 +881,14 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> +#else
> + ERRMSG("lzo compression unsupported\n");
> + ERRMSG("Try `make USELZO=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #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 +901,24 @@ readpage_kdump_compressed(unsigned long long paddr, void *bufptr)
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> +#else
> + ERRMSG("snappy compression unsupported\n");
> + ERRMSG("Try `make USESNAPPY=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #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);
> goto out_error;
> }
> +#else
> + ERRMSG("zstd compression unsupported\n");
> + ERRMSG("Try `make USEZSTD=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #endif
> }
>
> @@ -964,9 +984,14 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> + } 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");
> + out = FALSE;
> + goto out_error;
> + }
> +
> retlen = info->page_size;
> ret = lzo1x_decompress_safe((unsigned char *)buf, pd.size,
> (unsigned char *)bufptr, &retlen,
> @@ -975,9 +1000,14 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> +#else
> + ERRMSG("lzo compression unsupported\n");
> + ERRMSG("Try `make USELZO=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #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 +1020,24 @@ readpage_kdump_compressed_parallel(int fd_memory, unsigned long long paddr,
> ERRMSG("Uncompress failed: %d\n", ret);
> goto out_error;
> }
> +#else
> + ERRMSG("snappy compression unsupported\n");
> + ERRMSG("Try `make USESNAPPY=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #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);
> goto out_error;
> }
> +#else
> + ERRMSG("zstd compression unsupported\n");
> + ERRMSG("Try `make USEZSTD=on` when building.\n");
> + out = FALSE;
> + goto out_error;
> #endif
> }
>
> --
> 2.35.1
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