| Message ID | 20171106024319.32584-1-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Nov 06, 2017 at 10:43:18AM +0800, Qu Wenruo wrote: >[BUG] >Kernel panic when mounting with "-o compress" mount option. >KASAN will report like: >------ >================================================================== >BUG: KASAN: wild-memory-access in strncmp+0x31/0xc0 >Read of size 1 at addr d86735fce994f800 by task mount/662 >... >Call Trace: > dump_stack+0xe3/0x175 > kasan_report+0x163/0x370 > __asan_load1+0x47/0x50 > strncmp+0x31/0xc0 > btrfs_compress_str2level+0x20/0x70 [btrfs] > btrfs_parse_options+0xff4/0x1870 [btrfs] > open_ctree+0x2679/0x49f0 [btrfs] > btrfs_mount+0x1b7f/0x1d30 [btrfs] > mount_fs+0x49/0x190 > vfs_kern_mount.part.29+0xba/0x280 > vfs_kern_mount+0x13/0x20 > btrfs_mount+0x31e/0x1d30 [btrfs] > mount_fs+0x49/0x190 > vfs_kern_mount.part.29+0xba/0x280 > do_mount+0xaad/0x1a00 > SyS_mount+0x98/0xe0 > entry_SYSCALL_64_fastpath+0x1f/0xbe >------ > >[Cause] >For 'compress' and 'compress_force' options, its token doesn't expect >any parameter so its args[0] contains uninitialized data. >Accessing args[0] will cause above wild memory access. > >[Fix] >For Opt_compress and Opt_compress_force, set compression level to >Z_DEFAULT_COMPRESSION manually. > >NOTE: Don't set zlib compression level to 0 by default, which means no >compression. > >Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
On Mon, Nov 06, 2017 at 10:43:18AM +0800, Qu Wenruo wrote: > [BUG] > Kernel panic when mounting with "-o compress" mount option. > KASAN will report like: > ------ > ================================================================== > BUG: KASAN: wild-memory-access in strncmp+0x31/0xc0 > Read of size 1 at addr d86735fce994f800 by task mount/662 > ... > Call Trace: > dump_stack+0xe3/0x175 > kasan_report+0x163/0x370 > __asan_load1+0x47/0x50 > strncmp+0x31/0xc0 > btrfs_compress_str2level+0x20/0x70 [btrfs] > btrfs_parse_options+0xff4/0x1870 [btrfs] > open_ctree+0x2679/0x49f0 [btrfs] > btrfs_mount+0x1b7f/0x1d30 [btrfs] > mount_fs+0x49/0x190 > vfs_kern_mount.part.29+0xba/0x280 > vfs_kern_mount+0x13/0x20 > btrfs_mount+0x31e/0x1d30 [btrfs] > mount_fs+0x49/0x190 > vfs_kern_mount.part.29+0xba/0x280 > do_mount+0xaad/0x1a00 > SyS_mount+0x98/0xe0 > entry_SYSCALL_64_fastpath+0x1f/0xbe > ------ > > [Cause] > For 'compress' and 'compress_force' options, its token doesn't expect > any parameter so its args[0] contains uninitialized data. > Accessing args[0] will cause above wild memory access. > > [Fix] > For Opt_compress and Opt_compress_force, set compression level to > Z_DEFAULT_COMPRESSION manually. > > NOTE: Don't set zlib compression level to 0 by default, which means no > compression. But we never set the level to 0 at the point the compression actually happens. See zlib.c:zlib_set_level, if level is 0 then the level passed to zlib is 3. Z_DEFAULT_COMPRESSION is upstream zlib level 6, which is slower, we need zlib to stay in the real-time numbers. > @@ -507,8 +508,19 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, > token == Opt_compress_force || > strncmp(args[0].from, "zlib", 4) == 0) { > compress_type = "zlib"; > + > info->compress_type = BTRFS_COMPRESS_ZLIB; > - info->compress_level = > + /* > + * args[0] contains uninitialized data since > + * for these tokens we don't expect any > + * parameter. > + */ > + if (token == Opt_compress || > + token == Opt_compress_force) > + info->compress_level = > + Z_DEFAULT_COMPRESSION; > + else > + info->compress_level = > btrfs_compress_str2level(args[0].from); At least this will not screw up the levels, anything that's not recognized will become the default. > btrfs_set_opt(info->mount_opt, COMPRESS); > btrfs_clear_opt(info->mount_opt, NODATACOW); -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2017年11月15日 23:11, David Sterba wrote: > On Mon, Nov 06, 2017 at 10:43:18AM +0800, Qu Wenruo wrote: >> [BUG] >> Kernel panic when mounting with "-o compress" mount option. >> KASAN will report like: >> ------ >> ================================================================== >> BUG: KASAN: wild-memory-access in strncmp+0x31/0xc0 >> Read of size 1 at addr d86735fce994f800 by task mount/662 >> ... >> Call Trace: >> dump_stack+0xe3/0x175 >> kasan_report+0x163/0x370 >> __asan_load1+0x47/0x50 >> strncmp+0x31/0xc0 >> btrfs_compress_str2level+0x20/0x70 [btrfs] >> btrfs_parse_options+0xff4/0x1870 [btrfs] >> open_ctree+0x2679/0x49f0 [btrfs] >> btrfs_mount+0x1b7f/0x1d30 [btrfs] >> mount_fs+0x49/0x190 >> vfs_kern_mount.part.29+0xba/0x280 >> vfs_kern_mount+0x13/0x20 >> btrfs_mount+0x31e/0x1d30 [btrfs] >> mount_fs+0x49/0x190 >> vfs_kern_mount.part.29+0xba/0x280 >> do_mount+0xaad/0x1a00 >> SyS_mount+0x98/0xe0 >> entry_SYSCALL_64_fastpath+0x1f/0xbe >> ------ >> >> [Cause] >> For 'compress' and 'compress_force' options, its token doesn't expect >> any parameter so its args[0] contains uninitialized data. >> Accessing args[0] will cause above wild memory access. >> >> [Fix] >> For Opt_compress and Opt_compress_force, set compression level to >> Z_DEFAULT_COMPRESSION manually. >> >> NOTE: Don't set zlib compression level to 0 by default, which means no >> compression. > > But we never set the level to 0 at the point the compression actually > happens. See zlib.c:zlib_set_level, if level is 0 then the level > passed to zlib is 3. Z_DEFAULT_COMPRESSION is upstream zlib level 6, > which is slower, we need zlib to stay in the real-time numbers. Right, I missed that. So should I still use 0, or use separate macro like BTRFS_DEFAULT_ZLIB_LEVEL? Thanks, Qu > >> @@ -507,8 +508,19 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, >> token == Opt_compress_force || >> strncmp(args[0].from, "zlib", 4) == 0) { >> compress_type = "zlib"; >> + >> info->compress_type = BTRFS_COMPRESS_ZLIB; >> - info->compress_level = >> + /* >> + * args[0] contains uninitialized data since >> + * for these tokens we don't expect any >> + * parameter. >> + */ >> + if (token == Opt_compress || >> + token == Opt_compress_force) >> + info->compress_level = >> + Z_DEFAULT_COMPRESSION; >> + else >> + info->compress_level = >> btrfs_compress_str2level(args[0].from); > > At least this will not screw up the levels, anything that's not > recognized will become the default. > >> btrfs_set_opt(info->mount_opt, COMPRESS); >> btrfs_clear_opt(info->mount_opt, NODATACOW); > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On Thu, Nov 16, 2017 at 08:49:47AM +0800, Qu Wenruo wrote: > > But we never set the level to 0 at the point the compression actually > > happens. See zlib.c:zlib_set_level, if level is 0 then the level > > passed to zlib is 3. Z_DEFAULT_COMPRESSION is upstream zlib level 6, > > which is slower, we need zlib to stay in the real-time numbers. > > Right, I missed that. > > So should I still use 0, or use separate macro like > BTRFS_DEFAULT_ZLIB_LEVEL? BTRFS_DEFAULT_ZLIB_LEVEL would be better, as this would address https://patchwork.kernel.org/patch/10021441/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
================================================================== BUG: KASAN: wild-memory-access in strncmp+0x31/0xc0 Read of size 1 at addr d86735fce994f800 by task mount/662 ... Call Trace: dump_stack+0xe3/0x175 kasan_report+0x163/0x370 __asan_load1+0x47/0x50 strncmp+0x31/0xc0 btrfs_compress_str2level+0x20/0x70 [btrfs] btrfs_parse_options+0xff4/0x1870 [btrfs] open_ctree+0x2679/0x49f0 [btrfs] btrfs_mount+0x1b7f/0x1d30 [btrfs] mount_fs+0x49/0x190 vfs_kern_mount.part.29+0xba/0x280 vfs_kern_mount+0x13/0x20 btrfs_mount+0x31e/0x1d30 [btrfs] mount_fs+0x49/0x190 vfs_kern_mount.part.29+0xba/0x280 do_mount+0xaad/0x1a00 SyS_mount+0x98/0xe0 entry_SYSCALL_64_fastpath+0x1f/0xbe ------ [Cause] For 'compress' and 'compress_force' options, its token doesn't expect any parameter so its args[0] contains uninitialized data. Accessing args[0] will cause above wild memory access. [Fix] For Opt_compress and Opt_compress_force, set compression level to Z_DEFAULT_COMPRESSION manually. NOTE: Don't set zlib compression level to 0 by default, which means no compression. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/super.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 65af029559b5..14258671da84 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -42,6 +42,7 @@ #include <linux/cleancache.h> #include <linux/ratelimit.h> #include <linux/btrfs.h> +#include <linux/zlib.h> #include "delayed-inode.h" #include "ctree.h" #include "disk-io.h" @@ -507,8 +508,19 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, token == Opt_compress_force || strncmp(args[0].from, "zlib", 4) == 0) { compress_type = "zlib"; + info->compress_type = BTRFS_COMPRESS_ZLIB; - info->compress_level = + /* + * args[0] contains uninitialized data since + * for these tokens we don't expect any + * parameter. + */ + if (token == Opt_compress || + token == Opt_compress_force) + info->compress_level = + Z_DEFAULT_COMPRESSION; + else + info->compress_level = btrfs_compress_str2level(args[0].from); btrfs_set_opt(info->mount_opt, COMPRESS); btrfs_clear_opt(info->mount_opt, NODATACOW);