proc: #68991 Fix GPF in /proc/$PID/map_files
PATCH 1/1 proc: #68991 Fix GPF in /proc/$PID/map_files
https://bugzilla.kernel.org/show_bug.cgi?id=68991
The expected logic of proc_map_files_get_link() is either to return 0 and initialize 'path' or return an error and leave 'path' uninitialized. By the time dname_to_vma_addr() returns 0 the corresponding vma may have already be gone. In this case the path is not initialized but the return value is still 0. This results in 'general protection fault' inside d_path().
Steps to reproduce:CONFIG_CHECKPOINT_RESTORE=y
fd = open(...);
while (1) {
mmap(fd, ...);
munmap(fd, ...);
}ls -la /proc/$PID/map_files
---
fs/proc/base.c +1 -0
@@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)if (rc) goto out_mmput; + rc = -ENOENT ;down_read (&mm->mmap_sem); vma =find_exact_vma (mm, vm_start, vm_end);if (vma && vma->vm_file) {
Quoted 17 lines · Artem Fetishev
https://bugzilla.kernel.org/show_bug.cgi?id=68991
The expected logic of
proc_map_files_get_link()is either to return 0 and initialize 'path' or return an error and leave 'path' uninitialized. By the timedname_to_vma_addr()returns 0 the corresponding vma may have already be gone. In this case the path is not initialized but the return value is still 0. This results in 'general protection fault' insided_path().Steps to reproduce:
CONFIG_CHECKPOINT_RESTORE=yfd = open(...);
while (1) { mmap(fd, ...); munmap(fd, ...); }
Quoted 4 lines
ls -la
/proc/$PID/map_filesSigned-off-by Artem Fetishev <[email protected]>Signed-off-by Aleksandr Terekhov <[email protected]>
Quoted 15 lines
---
fs/proc/base.c +1
-0@@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)if (rc) goto out_mmput; + rc = -ENOENT ;down_read (&mm->mmap_sem); vma =find_exact_vma (mm, vm_start, vm_end);if (vma && vma->vm_file) {.
Cyrill Gorcunov
Acked-byQuoted 18 lines · Pavel Emelyanov
Quoted 17 lines · Artem Fetishev
https://bugzilla.kernel.org/show_bug.cgi?id=68991
The expected logic of
proc_map_files_get_link()is either to return 0 and initialize 'path' or return an error and leave 'path' uninitialized. By the timedname_to_vma_addr()returns 0 the corresponding vma may have already be gone. In this case the path is not initialized but the return value is still 0. This results in 'general protection fault' insided_path().Steps to reproduce:
CONFIG_CHECKPOINT_RESTORE=yfd = open(...);
while (1) { mmap(fd, ...); munmap(fd, ...); }
Quoted 6 lines
Quoted 4 lines
ls -la
/proc/$PID/map_filesSigned-off-by Artem Fetishev <[email protected]>Signed-off-by Aleksandr Terekhov <[email protected]>Acked-by Pavel Emelyanov <[email protected]>
Good catch, thanks!
I suppose this is a stable@ material.
Quoted 17 lines · Artem Fetishev
https://bugzilla.kernel.org/show_bug.cgi?id=68991
The expected logic of
proc_map_files_get_link()is either to return 0 and initialize 'path' or return an error and leave 'path' uninitialized. By the timedname_to_vma_addr()returns 0 the corresponding vma may have already be gone. In this case the path is not initialized but the return value is still 0. This results in 'general protection fault' insided_path().Steps to reproduce:
CONFIG_CHECKPOINT_RESTORE=yfd = open(...);
while (1) { mmap(fd, ...); munmap(fd, ...); }
Quoted 4 lines
ls -la
/proc/$PID/map_filesSigned-off-by Artem Fetishev <[email protected]>Signed-off-by Aleksandr Terekhov <[email protected]>
Quoted 17 lines
---
fs/proc/base.c +1
-0@@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)if (rc) goto out_mmput; + rc = -ENOENT ;down_read (&mm->mmap_sem); vma =find_exact_vma (mm, vm_start, vm_end);if (vma && vma->vm_file) {_______________________________________________
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