Messages in this thread | | | From | Vanessa Page <> | Subject | Re: [PATCH] jffs2: correct logic when creating a hole in jffs2_write_begin | Date | Mon, 25 Jul 2022 22:08:57 +0000 |
| |
You lame ass stalking motherfucker. You are committing a crime and I have reported you to the police.
Koop😂😂😑😑😑😎😄😄😴😴👀👀💁🙈🙈🙈🙈💁👀👀😑💁😁😳😎😴😑👀😑😄🤣🤣😀😃😑😴😄🤥🤫😥😰🥵🥵😡😡🤬🤯😭😭😟😟🥳🤩🥸🥸🥸🙁😩🥺☹️😣😔😔😔😖😣😢😡🥶😰😰😥😥😶🌫️🤬🤬🤬🤯😶🌫️🥶😰😰🤫🤫😓🤯🤯🤯 Ooiggvklpoure🤬🤬🤬🤬🤬🤬🤬🤬🤬🤬🤯🤯🤯🤯🤯🤯🤯🤯🤯🤫😓🤬🤯🤯🤬🤬🙁😒😍😒😒😎🥸🤩🥳😟😖🥺😩😩🤩🥳🥳😟😖😣🙁😩☹️😟😫😤😭🤬🤩🤩🥸😎🙁😩😡😵😪😧🤥🤥😯😵🤮😬🤥😓🤗🤗😶😲🤤🤐🤒🤕😵💫😵💫😵💫😵💫😵💫😵💫😵💫😵💫😵💫😵💫😵💫🤑😼😽☠️💀💀👻👻👻👹👹👺👽👽💀💀👻💀💀💀☠️☠️☠️☠️
> On Jul 25, 2022, at 1:04 AM, Vanessa Page <Vebpe@outlook.com> wrote: > > 🥰🥰🥰🥰🥰🥰🥰🥰🥰😍👌😍👌😍😍😍😍😍☺️☺️☺️☺️☺️💕💕😚😚😚😚🥰😚😍😍😍😚😚😍☺️☺️☺️😍💕😚🥰🥰😍☺️☺️😚🥰😍☺️😍🥰😍☺️☺️💕🥰🥰😍☺️☺️😊 > > Sent from my iPhon✌️ > >> On Jul 25, 2022, at 1:01 AM, Yifei Liu <yifeliu@cs.stonybrook.edu> wrote: >> >> Bug description and fix: >> >> 1. Write data to a file, say all 1s from offset 0 to 16. >> >> 2. Truncate the file to a smaller size, say 8 bytes. >> >> 3. Write new bytes (say 2s) from an offset past the original size of the >> file, say at offset 20, for 4 bytes. This is supposed to create a "hole" >> in the file, meaning that the bytes from offset 8 (where it was truncated >> above) up to the new write at offset 20, should all be 0s (zeros). >> >> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount >> and remount) the f/s. >> >> 5. Check the content of the file. It is wrong. The 1s that used to be >> between bytes 9 and 16, before the truncation, have REAPPEARED (they should >> be 0s). >> >> We wrote a script and helper C program to reproduce the bug >> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can >> make them available to anyone. >> >> The above example is shown when writing a small file within the same first >> page. But the bug happens for larger files, as long as steps 1, 2, and 3 >> above all happen within the same page. >> >> The problem was traced to the jffs2_write_begin code, where it goes into an >> 'if' statement intended to handle writes past the current EOF (i.e., writes >> that may create a hole). The code computes a 'pageofs' that is the floor >> of the write position (pos), aligned to the page size boundary. In other >> words, 'pageofs' will never be larger than 'pos'. The code then sets the >> internal jffs2_raw_inode->isize to the size of max(current inode size, >> pageofs) but that is wrong: the new file size should be the 'pos', which is >> larger than both the current inode size and pageofs. >> >> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to >> the difference between the pageofs minus current inode size; instead it >> should be the current pos minus the current inode size. Finally, >> inode->i_size was also set incorrectly. >> >> The patch below fixes this bug. The bug was discovered using a new tool >> for finding f/s bugs using model checking, called MCFS (Model Checking File >> Systems). >> >> Signed-off-by: Yifei Liu <yifeliu@cs.stonybrook.edu> >> Signed-off-by: Erez Zadok <ezk@cs.stonybrook.edu> >> Signed-off-by: Manish Adkar <madkar@cs.stonybrook.edu> >> --- >> fs/jffs2/file.c | 15 +++++++-------- >> 1 file changed, 7 insertions(+), 8 deletions(-) >> >> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c >> index ba86acbe12d3..0479096b96e4 100644 >> --- a/fs/jffs2/file.c >> +++ b/fs/jffs2/file.c >> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, >> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode); >> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb); >> pgoff_t index = pos >> PAGE_SHIFT; >> - uint32_t pageofs = index << PAGE_SHIFT; >> int ret = 0; >> >> jffs2_dbg(1, "%s()\n", __func__); >> >> - if (pageofs > inode->i_size) { >> - /* Make new hole frag from old EOF to new page */ >> + if (pos > inode->i_size) { >> + /* Make new hole frag from old EOF to new position */ >> struct jffs2_raw_inode ri; >> struct jffs2_full_dnode *fn; >> uint32_t alloc_len; >> >> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n", >> - (unsigned int)inode->i_size, pageofs); >> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n", >> + (unsigned int)inode->i_size, (uint32_t)pos); >> >> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len, >> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE); >> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, >> ri.mode = cpu_to_jemode(inode->i_mode); >> ri.uid = cpu_to_je16(i_uid_read(inode)); >> ri.gid = cpu_to_je16(i_gid_read(inode)); >> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs)); >> + ri.isize = cpu_to_je32((uint32_t)pos); >> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW()); >> ri.offset = cpu_to_je32(inode->i_size); >> - ri.dsize = cpu_to_je32(pageofs - inode->i_size); >> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size); >> ri.csize = cpu_to_je32(0); >> ri.compr = JFFS2_COMPR_ZERO; >> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8)); >> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping, >> goto out_err; >> } >> jffs2_complete_reservation(c); >> - inode->i_size = pageofs; >> + inode->i_size = pos; >> mutex_unlock(&f->sem); >> } >> >> -- >> 2.25.1 >> >> >> ______________________________________________________ >> Linux MTD discussion mailing list >> http://lists.infradead.org/mailman/listinfo/linux-mtd/
| |